A vacuum circuit breaker comprising: a grounded tank in which an insulating gas is encapsulated, the grounded tank having a tubular shape; a vacuum valve insulatively supported inside the grounded tank, the vacuum valve including a movable contact, a stationary contact, a vacuum container in which the movable contact and the stationary contact are housed, a movable conductor electrically connected to the movable contact, the movable conductor extending out of the vacuum container, and a tubular bellows having one end connected to the movable conductor and an opposite end connected to the vacuum container; a movable-side bushing conductor set in a bushing extending above the grounded tank, the movable-side bushing conductor having a tubular shape; a slider movably disposed inside the movable-side bushing conductor; a movable-side frame that is set adjacent to an outside of the vacuum container in a portion where the movable conductor extends out of the vacuum container, communicates with a space inside a tube of the bellows, and electrically connects a lower end of the movable-side bushing conductor to the movable conductor; wherein the lower end of the movable-side bushing conductor is connected to an opening of the movable-side frame; an operation rod having one end portion protruding to an outside of the grounded tank and an opposite end portion connected to the movable conductor outside the vacuum container; an operating device set outside the grounded tank to move the operation rod along an axial direction of the grounded tank; a movable-side support plate having a hole formed therein, through which the operation rod passes and covering an end of the grounded tank where the operation rod extends out of the grounded tank; and a packing set in the hole to close a gap between the operation rod and the movable-side support plate in a watertight state. a grounded tank in which an insulating gas is encapsulated, the grounded tank having a tubular shape; a vacuum valve insulatively supported inside the grounded tank, the vacuum valve including a movable contact, a stationary contact, a vacuum container in which the movable contact and the stationary contact are housed, a movable conductor electrically connected to the movable contact, the movable conductor extending out of the vacuum container, and a tubular bellows having one end connected to the movable conductor and an opposite end connected to the vacuum container; a movable-side bushing conductor set in a bushing extending above the grounded tank, the movable-side bushing conductor having a tubular shape; a slider movably disposed inside the movable-side bushing conductor; a movable-side frame that is set adjacent to an outside of the vacuum container in a portion where the movable conductor extends out of the vacuum container, communicates with a space inside a tube of the bellows, and electrically connects a lower end of the movable-side bushing conductor to the movable conductor; wherein the lower end of the movable-side bushing conductor is connected to an opening of the movable-side frame; an operation rod having one end portion protruding to an outside of the grounded tank and an opposite end portion connected to the movable conductor outside the vacuum container; an operating device set outside the grounded tank to move the operation rod along an axial direction of the grounded tank; a movable-side support plate having a hole formed therein, through which the operation rod passes and covering an end of the grounded tank where the operation rod extends out of the grounded tank; and a packing set in the hole to close a gap between the operation rod and the movable-side support plate in a watertight state.