In an apparatus and a method for replacing a working-object of a processing machine,
there are provided a working-object replacing support (6), a working-object moving passage (12) and a push/pull drive means (18) for the working-objects (5a) (5b). The push/pull drive means (18) is provided with a push/pull drive device (19), a push/pull engaging member pedestal (20), a push/pull transmission member (21), a guide rail (22) and a push/pull engaging member (23). An engaging portion (59) of the engaging member (23) is adapted to be shifted to a position lower than height positions of lower surfaces of engaged portions (25) (26) of the working-objects (5a) (5b) under the changed over condition to the disengagement position (Y) and at least to face upward so as to be engaged with the engaged portions (25) (26) from below under the changed over condition to the engagement position (X).