Provided is a trip mechanism for DC molded case circuit breaker, in which the insulating distance between the poles increases without any increase in whole product size, thereby reliably providing a trigger output against an over current and a fault current instantaneous breaking required. The trip mechanism includes a trip mechanism part including an instantaneous trip mechanism, the instantaneous trip mechanism including a movable member to operate according to a fault current instantaneous breaking required, and a thermal trip mechanism including a bimetal to operate according to an over current, the trip mechanism part being provided for one of two adjacent poles; a crossbar that is rotatable by contacting and pressing of the movable member of the instantaneous trip mechanism or the bimetal of the thermal trip mechanism; and a shooter that is provided to be rotatable by contacting of the crossbar rotating.