The invention provides a battery pack, which comprises a bare cell, a support member positioned at the top of the bare cell and a top case that covers the support member. In the battery pack, a protruding portion is formed in an end of the support member, and a receiving portion is formed at a position corresponding to the protruding portion in the top case. Accordingly, the protruding portion is inserted into the receiving portion, so that it is possible to provide the battery pack to be stronger against external impact.