An operation method of an electric press working machine including a frame body, a crown, and a plurality of support posts, a first slide that slides on the support posts, a second slide that slides on the support posts, a first-side drive source that drives the first slide, a second-side drive source that drives the second slide, and either a first upper die that is attached to correspond to the first slide or a second upper die that is attached to correspond to the second slide or both. The method includes: a step of moving the first and second slides to a first position; a step of moving the second slide to a second position while keeping the first slide at the first position; and a step of moving the second slide to a third position while keeping the first slide at the first position.