Battery pack

A battery pack is disclosed. The battery pack includes: a sub-holder assembly including a first sub-holder and a second sub-holder adjacent to each other, each of the first sub-holder and the second sub-holder accommodating a plurality of battery cells, and including side portions extending in different first and second directions; a first inner plate and a first outer plate at an inner position and an outer position of the sub-retainer assembly, respectively, and extending in a first direction, with the first sub-retainer being between the first inner plate and the first outer plate; a cooling plate below the first sub-holder and the second sub-holder in the third direction; and a fastening member. The first inner plate and the first outer plate include: an upper locking protrusion and a lower locking protrusion protruding toward the upper surface and the lower surface of the first sub-retainer, respectively, in the third direction; and a nut member disposed in the first direction together with the lower loc