Provided is a device having a novel configuration and adapted to assist joint exercise. A device for assisting joint exercise (10) that assists bending and extending of a joint including: a flexible assist force transmission section (12) a first mounting section (14) and a second mounting section (16), which are provided at both end portions of the assist force transmission section (12), the first mounting section (14) adapted to be mounted on one site and the second mounting section (16) adapted to be mounted on another site sandwiching a users joint a drive source (40) provided that exerts tensile force between the first mounting section (14) and the second mounting section (16) through the assist force transmission section (12), wherein at least a portion of the assist force transmission section (12) is elastically deformable in an acting direction of the tensile force by the drive source (40).
