The Biomen are the descendants of five people showered with Bio Particles centuries ago. They are found by Peebo in modern times and given Techno Braces (テクノブレス, Tekuno Buresu?) to communicate and transform. To transform individually they call their color and number and to transform as a group they call Bioman, By raising their hands, clenching their left fists and holding them with their right palms. Although in episode 1, they transformed one by one shouting "Bioman", since they do not know their respective ranger designations; their designations may have later came from their order of transformation (Shirō, Shingo, Ryūta, Mika and Hikaru). Along with their Bio Swords (バイオソード, Baio Sōdo?), a versatile sidearm with sword, dagger, and blaster modes, the Biomen are fairly unique in that they have a variety of team attacks, including the Bio Electron Beam (バイオエレクトロビーム, Baio Erekutoron Bīmu?), and the Miracle Laser (ミラクルレーザー, Mirakuru Rēzā?).
- Shirō Gō (郷史朗, Gō Shirō?)/Red One (レッドワン, Reddo Wan?)
- At 24, he is the pilot of the first Japanese space shuttle. Unfortunately, he gets caught in the crossfire just as the Gear begins the invasion. In him, passion and responsibility unite in an unusual combination. He possessed a charm since he was born. He grew up believing that his father was dead. However, after meeting Professor Shibata, even he is not so sure. Armed with Fire Sword (ファイヤーソード, Faiyā Sōdo?) and Spark Sword (スパークソード, Supāku Sōdo?), and using the Super Electronic Radar (超電子レーダー, Chōdenshi Rēdā?) special attack. 16 years after Bioman ended, Red One appeared in Hyakujū Sentai Gaoranger vs. Super Sentai as one of 24 Red Rangers introduced by his Liveman successor Red Falcon, to inspire the Gaoranger team. In the English version, his name is Kenny.
- Shingo Takasugi (高杉真吾, Takasugi Shingo?)/Green Two (グリーンツー, Gurīn Tsū?)
- He is a 23-year-old race car driver. Shingo can be very tough to enemies yet very kind to children, for whom he has a soft spot. Yet despite his bravado, there are times when he doubts his own abilities. Yet despite these doubts, he knows what he must do and does them as well as possible. He is the designated driver of the Bio Turbo. Armed with Hurricane Sword (ハリケーンソード, Harikēn Sōdo?) and Green Boomerang (グリーンブメラング, Gurīn Bumerangu?), as well as Super Electronic Scope (超電子スコープ, Chōdenshi Sukōpu?) and Break Action (ブレイクアクション, Bureiku Akushon?) special attacks. English version is: Sammy
- Ryūta Nanbara (南原竜太, Nanbara Ryūta?)/Blue Three (ブルースリー, Burū Surī?)
- A water sportsman who, at 19 years of age, is boyish and adventurous; he loves to explore and discover things new. His years of diving have made him very nimble; thus, he is very skilled in stealth techniques. He wields the Super Electronic Ear (超電子イヤー, Chōdenshi Iyā?) and Elec-Sword (エレキソード, Ereki Sōdo?). His special attack is Super Sky Diving (スーパースカイダイビング, Sūpā Sukai Daibingu?). English version is: Franky
- Mika Koizumi (小泉ミカ, Koizumi Mika?, 1-9)/Yellow Four I (1初代イエローフォー, Shodai Ierō Fō?, 1-10)
- A photographer who dreams of following in her brother's footseps to photograph the wildlife in Africa. Initially, she is hesitant to join the Bioman team. However, she is convinced when she realizes that if she does not fight, then the animals in Africa that she loves will eventually be in danger. She was killed by repeated Anti-Bio Particle blasts frthumb|300px|rightom the Bio Killer Gun to save the others (and she was severely blasted by Psygorn after the Bio Killer Gun ran out of ammunition) which Peebo later recalls during Silva's first appearance. Her weapon was the Thunder Sword (サンダーソード, Sandā Sōdo?). Her special attacks were Super Electronic Holography (超電子ホログラフィ, Chōdenshi Horogurafi?) and Yellow Flash. Near the end of episode 10, Bio Robo's eyes glowed activating her computer system in her helmet and later activated her super electronic holography from her visor showin a footage of her (which was actually her shot at the end credits). From the start of episode 10 up to her subsequent death, wake and/or funeral, she remained in her yellow 4 suit. English version is: Casey
- Jun Yabuki (矢吹ジュン, Yabuki Jun?)/Yellow Four II (2代目イエローフォー, Nidaime Ierō Fō?, 11-51)
- An Olympic archer. 19 years old, sometimes dressing up like an American Indian cowgirl/Indian hybrid outfit. After watching the Bioman in action, she tries to join them but is initially refused, even though Mika Koizumi had just died; the others were looking for another descendant of the original five who were bombarded with the Bio Particles. However, she proves her courage, and it was discovered that she also has Bio Particles. Her weapons are Bio Arrow (バイオアロー, Baio Arō?) and Thunder Sword (サンダーソード, Sandā Sōdo?). Her special attack is Super Electronic Holography (超電子ホログラフィ, Chōdenshi Horogurafi?). English version is: June
- Hikaru Katsuragi (桂木ひかる, Katsuragi Hikaru?)/Pink Five (ピンクファイブ, Pinku Faibu?)
- A 20-year-old carnival flutist. Sweet yet strong, and a mistress of disguise. An unusually strong spirit yet with a strong motherly instinct. She plays the flute both to calm her spirits and to strengthen her resolve. She is able to befriend the evil computer Brain and teach him about friendship, which pays off when Brain sacrifices himself to save the Bioman as well as the world from destruction. She is also the most emotional member of the team, especially when crying. She wields the Super Electronic Beamlight (超電子ビームライト, Chōdenshi Bīmuraito?), Pink Barrier (ピンクバリヤー, Pinku Bariyā?), and Laser Sword (レーザーソード, Rēzā Sōdo?). Her special attacks are Pink Flash (ピンクフラッシュ, Pinku Furasshu?) and Spin Chop (スピンチョップ, Supin Choppu?). Her name means light. English version is: Kimberly