BATTERY PACK

A battery pack includes battery cell including a discharge valve opened when an internal pressure exceeds a set pressure, and case housing battery cell. Exhaust duct through which a discharge gas is discharged from the discharge valve to an outside of the case is disposed in the case, a discharge side of exhaust duct is opened to the outside of the case, and an inflow side of the exhaust duct is opened to an inside of the case, a diffusion space of the discharge gas is provided inside case, the discharge valve ejects the discharge gas into the diffusion space, and the discharge gas of the diffusion space is discharged to the outside of the case via exhaust duct.