The present invention aims to reduce a size of a hinge portion and a device in an opening/closing mobile terminal device in which first and second housing members are opened/closed and turned on hinges. In the present invention, a second turning shaft (123) is provided to intersect with the first turning member so as to turn together with a first turning shaft (122) and provided turnably to the first turning shaft (122), first and second guiding member (126, 127) for restricting a turning angle of the second turning shaft (123) are provided in the first turning shaft (122). Also, a flexible board (140) is interposed in the first turning shaft (122) and a first turning bearing (133) in a position that stretches over a first housing member (101a) and a second housing member (101b). A first winding portion (154a) that is wound around an outer periphery of the first turning bearing (133) is formed on one end side of the flexible board (140) to turn together with the first turning shaft (122).