a battery cell including a discharge valve that opens when an internal pressure of the battery cell exceeds a set pressure; and

a case housing the battery cell,

wherein the case has a plurality of fume ventilation holes through which discharged gas jetted from the discharge valve is expelled out of the case,

wherein the case comprises an upper case and a lower case coupled together along an interface where respective opening ends of the upper case and the lower case meet,

wherein the interface is counter to a discharge valve side end surface of the battery cell,

the battery pack further comprises a flameproof cover disposed along the inner surface of the case and facing the interface of the upper case and the lower case, wherein the flameproof cover has a plate-shape, and is positioned on the inner surface of the case with a diffusion gap defined between the flameproof cover and the discharge valve side end surface,

an expansion space for the discharged gas diffused by the flameproof cover is provided inside the case,

a direction of expelling the discharged gas through the fume ventilation holes intersects a direction in which the discharged gas is jetted from the discharge valve,

the expansion space communicates with the diffusion gap and with inner openings of the fume ventilation holes on the inner surface of the case,

a direction changing portion of the gas flowing inside case is provided at a corner of the case, and

the discharged gas jetted from the discharge valve collides with the flameproof cover, fills the expansion space via the diffusion gap, is changed in direction in the expansion space to diffuse into the plurality of fume ventilation holes, and is expelled out of the case.