A head-mounted display device comprising: a frame including a first surface formed according to a face of a user; a wearing part formed to couple to at least a part of the frame so as to allow the frame to be fixed to the face; a mounting part formed as a cavity structure of the frame and configured to mount an external electronic device to a second surface of the frame, said electronic device being a portable mobile communication terminal that is useable as display; and one or more fastening parts configured to fix the external electronic device to the mounting part, characterised in that the one or more fastening parts include a connector fastening part and a terminal fastening part; wherein the connector fastening part comprises a connector holder including a connector connectable with the electronic device, wherein the connector holder is pivotable from a first inclined opening angle state toward the mounting part to be in a second state, in which second state the external electronic device, when coupled to the connector holder, lies against the second surface; wherein the terminal fastening part comprises a terminal holder and a locking flange that protrudes from an upper portion of the terminal holder, which locking flange is configured to lock the mounted external electronic device, which terminal holder is pivotable between a second inclined opening angle state toward the mounting part to be in a fixing state; wherein, when one end of the external electronic device is coupled to the connector holder and another end of the external electronic device is fixed by the terminal fastening part, the connector holder is adapted to pivot to the second state by a weight of the external electronic device, and the terminal holder is adapted to pivot to the fixing state to fix the external electronic device to the second surface. a frame including a first surface formed according to a face of a user; a wearing part formed to couple to at least a part of the frame so as to allow the frame to be fixed to the face; a mounting part formed as a cavity structure of the frame and configured to mount an external electronic device to a second surface of the frame, said electronic device being a portable mobile communication terminal that is useable as display; and one or more fastening parts configured to fix the external electronic device to the mounting part, characterised in that the one or more fastening parts include a connector fastening part and a terminal fastening part; wherein the connector fastening part comprises a connector holder including a connector connectable with the electronic device, wherein the connector holder is pivotable from a first inclined opening angle state toward the mounting part to be in a second state, in which second state the external electronic device, when coupled to the connector holder, lies against the second surface; wherein the terminal fastening part comprises a terminal holder and a locking flange that protrudes from an upper portion of the terminal holder, which locking flange is configured to lock the mounted external electronic device, which terminal holder is pivotable between a second inclined opening angle state toward the mounting part to be in a fixing state; wherein, when one end of the external electronic device is coupled to the connector holder and another end of the external electronic device is fixed by the terminal fastening part, the connector holder is adapted to pivot to the second state by a weight of the external electronic device, and the terminal holder is adapted to pivot to the fixing state to fix the external electronic device to the second surface.