A gas circuit breaker for switching breaking and turning-on of an electric current, comprising: a sealed container filled with an arc-extinguishing gas; a pair of fixed arc electrodes (30a, 30b) arranged in said sealed container to be opposite to each other; a trigger electrode movably arranged between said fixed arc electrodes and generating an arc discharge according to movement; a pressurization unit pressuring and increasing a pressure of said arc-extinguishing gas with pressurization means; and a pressure accumulation unit in communication with said pressurization unit and accumulating said pressurized arc-extinguishing gas, wherein said trigger electrode is an open and close means for switching said pressure accumulation unit into a closed state or an open state, and said pressure accumulation unit is switched to said closed state in a first half of breaking of said electric current, and said pressure accumulation unit is switched to said open state in a latter half of breaking of said electric current, so that said arc-extinguishing gas in said pressure accumulation unit is guided to said arc discharge, characterized in that: said pressurization means seals a communication portion between said pressurization unit and said pressure accumulation unit in accordance with movement, and separates said pressurization unit and said pressure accumulation unit in terms of pressure; and said pressurization unit further comprises a pressure release means for releasing said pressure of said pressurization unit in accordance with movement in which said pressurization means moves to a position where said communication portion is sealed. a sealed container filled with an arc-extinguishing gas; a pair of fixed arc electrodes (30a, 30b) arranged in said sealed container to be opposite to each other; a trigger electrode movably arranged between said fixed arc electrodes and generating an arc discharge according to movement; a pressurization unit pressuring and increasing a pressure of said arc-extinguishing gas with pressurization means; and a pressure accumulation unit in communication with said pressurization unit and accumulating said pressurized arc-extinguishing gas, wherein said trigger electrode is an open and close means for switching said pressure accumulation unit into a closed state or an open state, and said pressure accumulation unit is switched to said closed state in a first half of breaking of said electric current, and said pressure accumulation unit is switched to said open state in a latter half of breaking of said electric current, so that said arc-extinguishing gas in said pressure accumulation unit is guided to said arc discharge, characterized in that: said pressurization means seals a communication portion between said pressurization unit and said pressure accumulation unit in accordance with movement, and separates said pressurization unit and said pressure accumulation unit in terms of pressure; and said pressurization unit further comprises a pressure release means for releasing said pressure of said pressurization unit in accordance with movement in which said pressurization means moves to a position where said communication portion is sealed. said pressurization means seals a communication portion between said pressurization unit and said pressure accumulation unit in accordance with movement, and separates said pressurization unit and said pressure accumulation unit in terms of pressure; and said pressurization unit further comprises a pressure release means for releasing said pressure of said pressurization unit in accordance with movement in which said pressurization means moves to a position where said communication portion is sealed.