Gas circuit breaker

A gas circuit breaker includes a driving side electrode having a driving side main contact and a driving side arc contact, and a driven side electrode having a driven side main contact and a driven side arc contact in a sealed tank. The driving side electrode is connected to an operation device. The driven side electrode is coupled to a bidirectional driving mechanism unit. A sliding guide, on which the driven side main contact slides, is provided on an inner periphery side of the driven side main contact. The driven side main contact is energized by a coil spring in a direction of the sliding guide and has two contact surfaces. Only during normal conduction, one of the contact surfaces contacts a projected portion of the sliding guide and the other of the contact surfaces contacts the driving side main contact.