When the pressure in the battery case is increased, the gas discharge flow rate is secured sufficiently. This battery case (30) is a battery case in which a battery (2) is housed in a housing (10). The battery case (30) includes a gas discharge mechanism (G). The gas discharge mechanism (G) includes a gas discharge port (51) that opens in a wall plate (43) that covers a periphery of the housing (10), and a lid part (35m). The lid part (35m) is disposed to cover the gas discharge port (51) from inside the wall plate (43), and is fixed on the housing (10) side.