A closing mechanism applicable to an electronic device, computer device or docking device comprises a housing, a closing member, a base, an elastomer and a support. Sliding portion and the corresponding chutes are disposed at the bottom portions of the closing member and the base, respectively. Both ends of the elastomer are fastened to the hooks of the closing member and base; thus, via elasticity, the elastomer automatically closes the opening of the I/O port of the closing mechanism.