Head-mounted display device

A head-mounted display device includes a belt body, a buckle assembly disposed at the belt body and an electronic module disposed at the buckle assembly. The buckle assembly includes a base movably fixed to the belt body and a cover detachably disposed at the base. One of the base and the cover includes a sliding rail, the other includes a sliding member. One of the base and the cover includes an arm and a hook protruding from the arm, the other includes an engaging indent. The electronic module including a display module is disposed at the cover. The hook is engaged with the engaging indent so that the cover is fixed to the base. While bending the arm, the hook is disengaged from the engaging indent, the cover is able to depart from the base, so that the electronic module is separated from the belt body.