A slide lock device for a press machine that locks a shaft member that rotates together with raising and lowering operation of a slide that is supported by a main body frame of a press machine so that the shaft member cannot rotate, comprising a flange member having a barrel portion that is fitted over the shaft member and is fixed thereto so as not to be rotatable relative thereto and a flange portion that extends from an end portion of the barrel portion along a plane orthogonal to an axis of the shaft member up to an external periphery, an annular main body member that is fitted over the barrel portion so as to be rotatable with respect thereto and that is fixed to the main body frame, a plurality of reception holes formed in the main body member and parallel to the axis, a plurality of pin members installed in the plurality of reception holes so as to be capable of shifting forward and backward therein, and a plurality of arcuate entry holes formed in the flange portion, and that lock the shaft member via the flange member so that the shaft member cannot rotate by driving the plurality of pin members forward toward the flange portion by fluid pressure and inserting them into the plurality of entry holes, characterized by comprising: an annular piston member that is installed within an annular cylinder bore formed in the main body member so as to be shiftable through a predetermined stroke in a direction parallel to the axis, and in which the plurality of reception holes are formed; an annular first fluid pressure working chamber defined within the annular cylinder bore for driving the annular piston member forward toward the flange portion; a second fluid pressure working chamber defined within the annular cylinder bore for driving the annular piston member backward in the direction to distance from the flange portion; and a first opposing wall portion formed in the main body member so as to position in a vicinity of the flange portion from a side of the annular piston, and a plurality of first support holes formed in the first opposing wall portion so as to oppose the plurality of reception holes; wherein the plurality of pin members are respectively installed in the plurality of reception holes and the plurality of first support holes so as to shift freely along the axial direction, and are adapted to be capable of receiving fluid pressure in said first fluid pressure working chamber; and are adapted so that, when the annular piston member is driven forward by fluid pressure in the first fluid pressure working chamber, the plurality of pin members are put into inserted positions in which the plurality of pin members are inserted into the entry holes or into insertable positions, by fluid pressure in the first fluid pressure working chamber; and, when the annular piston member is driven backward by fluid pressure in the second fluid pressure working chamber, the plurality of pin members are changed over into retracted positions in which they are backed up out of the entry holes toward the annular piston member. an annular piston member that is installed within an annular cylinder bore formed in the main body member so as to be shiftable through a predetermined stroke in a direction parallel to the axis, and in which the plurality of reception holes are formed; an annular first fluid pressure working chamber defined within the annular cylinder bore for driving the annular piston member forward toward the flange portion; a second fluid pressure working chamber defined within the annular cylinder bore for driving the annular piston member backward in the direction to distance from the flange portion; and a first opposing wall portion formed in the main body member so as to position in a vicinity of the flange portion from a side of the annular piston, and a plurality of first support holes formed in the first opposing wall portion so as to oppose the plurality of reception holes; wherein the plurality of pin members are respectively installed in the plurality of reception holes and the plurality of first support holes so as to shift freely along the axial direction, and are adapted to be capable of receiving fluid pressure in said first fluid pressure working chamber; and are adapted so that, when the annular piston member is driven forward by fluid pressure in the first fluid pressure working chamber, the plurality of pin members are put into inserted positions in which the plurality of pin members are inserted into the entry holes or into insertable positions, by fluid pressure in the first fluid pressure working chamber; and, when the annular piston member is driven backward by fluid pressure in the second fluid pressure working chamber, the plurality of pin members are changed over into retracted positions in which they are backed up out of the entry holes toward the annular piston member.