Provided is a knee joint stimulation device that makes it possible to apply effective stimulation to the knee joint. A knee joint stimulation device (1) is configured such that: a central shaft (5), which is provided to an upper part of a frame (4) erected on a base (2), and a motor (3) are coupled together by a crank (6)； the central shaft (5) can be rotated by the crank (6) that is driven by rotation of the motor (3)； a swing arm (7) of adjustable length is suspended from the central shaft (5)； a support plate section (8) on which a sole (91) of a user (9) who is sitting upright can be placed is provided at a lower end section of the swing arm (7)； and the support plate section (8) is such that in the state where the sole (91) of the user (9) has been placed on the support plate section (8), the length of the swing arm (7) is adjusted so that a center of rotation (92a) of a knee joint (92) of the user (9) matches the central shaft (5), thereby making it possible to move the sole (91) that has been placed on the support plate section (8) in a direction of flexion or direction of extension, centered on the knee joint (92), by swinging the swing arm (7).
