Disclosed is a molded case circuit breaker. The molded case circuit breaker includes include: a case; an interrupter assembly installed in the case, and provided with an arc gas outlet; an exhaustion guiding portion disposed between the interrupter assembly and the terminal portion; an exhaustion cover mounted to the case, with a structure to cover the exhaustion guiding portion; and exhaustion guides spaced from each other in the exhaustion guiding portion, in a direction perpendicular to an arc gas discharge direction, in a state where the gas divergence portion is disposed therebetween, the exhaustion guides forming the arc gas passage together with the gas divergence portion. Under such configuration, arc gas discharged out of the arc gas outlet can be rapidly discharged to outside through the exhaustion guides, without an eddy current.