Abstract: An apparatus for adjusting a slide stroke of a press machine comprising a press frame, a spindle rotatably mounted on the press frame, a first eccentric drum fixedly mounted on the spindle, a second eccentric drum rotatably mounted on the first eccentric drum, a connecting rod rotatably mounted on the second eccentric drum and a slide connected with the second eccentric drum through a plunger. A cylindrical member is rotatably and slidably mounted on the spindle and is adapted to be selectively connectible with the first eccentric drum. The cylindrical member is connected so as to rotate along with the second eccentric drum via a plate member which is rotatably mounted on the spindle and is adapted to slide within a guide groove formed in the second eccentric drum. The slide stroke is adjustable by rotating the second eccentric drum relative to the first eccentric drum.