A biological activity detection apparatus includes: a drive unit that actively or passively drives in conjunction with a limb motion of a subject; a periarticular detection unit that detects a periarticular physical quantity around a joint in association with the limb motion of the subject based on an output signal from the drive unit; a biological signal detection unit located at a body surface site of the subject with reference to the joint and includes an electrode group for detecting a biological signal of the subject, wherein an activity status of a musculoskeletal system and/or a transmission status of a peripheral nervous system around the joint are converted into quantitative musculoskeletal system data and/or nervous system data on the basis of the physical quantity acquired from the periarticular detection unit and a myogenic potential signal and a neural transmission signal which are acquired from the biological signal processing unit.