A method for assembling a keyswitch device includes: connecting a first covering portion to a surface of a first housing; connecting a second covering portion to a connection base comprising an engaging portion; rotatably engaging the engaging portion with an engaging structure; connecting the engaging structure to the first housing; and fixing a second housing to the first housing such that the first housing and the second housing constitute a recess communicating with the surface, wherein the engaging structure partially protrudes into the recess.