When a first bellows (171) contracts, a first connecting member (131) rotates with respect to an attachment member (150) with shaft members (AX1L, AX1R) as the central axes. As a result, the angle of the anterior of the human body formed by the lumbar external skeleton member (110) and the attachment member (150) when the joint movement assistance device (100) is worn expands and the lumbar joint changes from a bent state to an extended state. When second bellows (172L, 172R) contract, second connecting members (141L, 141R) rotate with respect to the attachment member (150) with shaft members (AX2L, AX2R) as the central axes. As a result, the angle of the anterior of the human body formed by the femoral external skeleton members and the attachment member (150) when the joint movement assistance device (100) is worn expands and the left and right hip joints change from a bent state to an extended state. As a result, it is possible to appropriately assist joint movement while achieving smooth joint movement.