This motion assistance device (1) being a wearable implement is provided with a frame (12) which is to be worn to cover a wearer from the dorsal side of the lumbar part through the right and left lateral lumbar parts, wherein, of the frame (12), the distance between a pair of mounting bodies (13), which are portions to be attached near the right and left lateral lumbar parts of the wearer, increases from the dorsal side to the ventral side of the lumbar part. For example, each of the mounting bodies (13) may constitute an end of the frame (12). Further, the mounting bodies (13) may have a substantially flat surface at the faces facing the right and left lateral lumbar parts of the wearer.
