To provide a compliance mechanism that can be stored in a space-saving manner in a robot joint mechanism.

A distortion ring 208 deformed in conjunction with motion of a first finger part 203 is arranged inside a worm wheel 207 in a structure pivotally supporting the first finger part 203 to a base part 202. The distortion ring 208 is deformed corresponding to a load along with transmission of driving force to the first finger part 203 via the distortion ring 208 when the worm wheel 207 is rotated while being driven by a servomotor in the base part 202. The force is directly transmitted to the first finger part 203 from the worm wheel 207 by the contact of a stopper protrusion 219 with the end part of a guide slit 220 when the worm wheel 207 is further rotated. The motion of the first finger part 203 involves the compliance in a range of allowing the stopper protrusion 219 to move in the guide slit since the driving force is transmitted via the deformable distortion ring 208.