Gas circuit breaker

A gas circuit breaker comprising:

• a sealed tank that includes a first conductor container and a second conductor container, which are provided with an insulating tube therebetween, and that is filled with an insulating gas;
• a fixed arcing contact provided on the first conductor container side;
• a movable arcing contact that is provided on the second conductor container side and moves such that the movable arcing contact is capable of coming into contact with and separating from the fixed arcing contact;
• a fixed conductive contact provided on the first conductor container side;
• a movable conductive contact that moves in accordance with contact and separation of the movable arcing contact and comes into contact with and separates from the fixed conductive contact;
• and
• a puffer unit that is provided on the second conductor container side and has a mechanical puffer chamber formed therein, the mechanical puffer chamber being formed by a cylinder that accommodates therein the movable conductive contact, wherein
• the puffer unit is arranged between the insulating tube and the second conductor container and is exposed to an outer periphery of the sealed tank, and
• a fin is formed on an outer periphery of the puffer unit.