A keyswitch device includes a connecting member and a keycap. The connecting member has an engaging shaft. The keycap includes a pressing body and a shaft hole structure. The pressing body has a bottom surface. The shaft hole structure is connected to the bottom surface and has an engaging trough and an inlet passage communicated with each other. The engaging shaft is rotatably engaged in the engaging trough. The inlet passage has a first inner wall and a second inner wall opposite and parallel to each other. The first inner wall and the second inner wall are inclined relative to the bottom surface of the pressing body.