A battery module comprising: a cell assembly including at least one battery cell; a cover plate covering a first surface of the cell assembly; and a bus bar frame covering a second surface adjacent to the first surface of the cell assembly, the bus bar frame being connected to the cover plate so as to be rotatable with respect to the cover plate, wherein the cover plate and the bus bar frame are connected by at least one connecting part, the connecting part including a fixing part protruding from a corner of the bus bar frame, the fixing part defining a bar shape extending along an axis parallel to the corner and having two opposing ends, the fixing part including an inclined surface so that a width of the fixing part defined orthogonal to the axis decreases towards both opposing ends, and a pair of accommodating parts protruding from the cover plate and including a groove part into which the two opposing ends of the fixing part are received, wherein the pair of accommodating parts include an accommodating inclined surface formed on at least a part of an inner surface of the pair of accommodating parts so that a gap defined between the pair of accommodating parts increases in a direction toward an upper surface of the cover plate, wherein there is a space (d) defined between the fixing part and the bus bar frame so that the fixing part includes a hooking surface formed opposite to the inclined surface across the width of the fixing part, and when the fixing part and the accommodating parts are connected, the inclined surface is inserted into the groove part along the accommodating inclined surface until the hooking surface comes in contact with the groove part. a cell assembly including at least one battery cell; a cover plate covering a first surface of the cell assembly; and a bus bar frame covering a second surface adjacent to the first surface of the cell assembly, the bus bar frame being connected to the cover plate so as to be rotatable with respect to the cover plate, wherein the cover plate and the bus bar frame are connected by at least one connecting part, the connecting part including a fixing part protruding from a corner of the bus bar frame, the fixing part defining a bar shape extending along an axis parallel to the corner and having two opposing ends, the fixing part including an inclined surface so that a width of the fixing part defined orthogonal to the axis decreases towards both opposing ends, and a pair of accommodating parts protruding from the cover plate and including a groove part into which the two opposing ends of the fixing part are received, wherein the pair of accommodating parts include an accommodating inclined surface formed on at least a part of an inner surface of the pair of accommodating parts so that a gap defined between the pair of accommodating parts increases in a direction toward an upper surface of the cover plate, wherein there is a space (d) defined between the fixing part and the bus bar frame so that the fixing part includes a hooking surface formed opposite to the inclined surface across the width of the fixing part, and when the fixing part and the accommodating parts are connected, the inclined surface is inserted into the groove part along the accommodating inclined surface until the hooking surface comes in contact with the groove part.