A slide lock apparatus that locks the slide of a press machine includes: a flange member fixed over the exterior of a shaft member that rotates together with raising and lowering operation of the slide, and having a flange portion that is parallel to a plane orthogonal to the axis of the shaft member; an annular main member fixed to the main frame of the press machine, and having an annular member facing the flange portion with a gap between them; a plurality of reception holes formed in the annular member; a plurality of pin members installed in the plurality of reception holes so as to be shiftable therein; a plurality of actuators that are capable of driving the plurality of pin members between retracted positions in which they are not advanced toward the flange portion and advanced positions in which they are advanced to states in which they penetrate into introduction holes in the flange portion; a first locking member that is capable of locking the plurality of pin members in their retracted positions; a first drive means that is capable of rotationally driving this first locking member between a locking position and an unlocking position; a second locking member that is capable of locking the plurality of pin members in their advanced positions; and a second drive means that is capable of rotationally driving this second locking member between a locking position and an unlocking position.