BATTERY PACK

To improve safety by suppressing a harmful effect caused by high-temperature discharged gas jetted from discharge valves of cells. A battery pack includes battery cell (1) including a discharge valve, and case (2) housing battery cell (1). Case (2) includes a plurality of fume ventilation holes (27) through which discharged gas jetted from the discharge valve is expelled out of the case, and diffusion gap (28) is provided between discharge valve side end surface (1a) of battery cell (1) and a case inner surface, with flameproof cover (6) disposed in diffusion gap (28). Additionally, expansion space (25) for the discharged gas diffused by flameproof cover (6) is provided inside case (2), and the direction of expelling the discharged gas is changed to a direction intersecting a direction in which the discharged gas is jetted form the discharge valve. Expansion space (25) communicates with diffusion gap (28) and with fume ventilation holes (27), and a direction changing portion that changes a direction of the flowing gas is provided at corners of the case. In the battery pack, the discharged gas jetted from the discharge valve collides with flameproof cover (6), fills expansion space (25) via diffusion gap (28), is changed in direction in expansion space (25) to diffuse into the plurality of fume ventilation holes (27), and is expelled out of the case.