The present disclosure relates to a massage apparatus including an arm massage part, the massage apparatus comprising: a frame connection part which connects a buttock frame provided in a main frame and a back frame provided in the main frame, and which rotates about a frame rotation axis on the basis of the movement of the back frame; a driving shaft which passes through the frame connection part and moves along an arc-shaped driving shaft slot on the basis of the movement of the back frame; and an arm massage frame holder which moves along a sliding rail on the basis of the movement of a plurality of links that transmit the movement of the driving shaft.

A headrest locking device comprising a headrest stay and a locking device which is provided in a headrest body which is supported by the headrest stay, wherein the locking device locks the relative movement of the headrest body in the height direction by engaging a notched groove formed in the headrest stay. The locking device comprising a lock plate which is engaged and disengaged against the notched groove by movement in the headrest width direction and a lock spring which urges the lock plate in the width direction to engage the notched groove. The lock plate and the notched groove have contact surfaces that contact each other in a planar manner at an angle facing forward or rearward oblique to the direction of force of the lock spring.

A headrest locking device comprising a headrest stay and a locking device which is provided in a headrest body which is supported by the headrest stay, wherein the locking device locks the relative movement of the headrest body in the height direction by engaging a notched groove formed in the headrest stay. The locking device comprising a lock plate which is engaged and disengaged against the notched groove by movement in the headrest width direction and a lock spring which urges the lock plate in the width direction to engage the notched groove. The lock plate and the notched groove have contact surfaces that contact each other in a planar manner at an angle facing forward or rearward oblique to the direction of force of the lock spring.