A head-mounted display device includes a wearable device, a display mainframe and a pivoting mechanism. The display mainframe includes a cover body and a display-receiving portion connected to one side of the cover body. The cover body is provided with a light transmissive area and an accommodation area in which the light transmissive area is arranged between the accommodation area and the display-receiving portion. The pivoting mechanism is pivotally connected to the wearable device and the display mainframe.