A portable terminal device comprising: a portable terminal that is provided with a first housing, a second housing and a coupling unit that couples the first and second housings (11, 21) rotatably about a first axis; and a cover that covers at least a portion of the portable terminal and that is foldable about a second axis parallel to the first axis, wherein a first end section of the second housing on the side opposite to the end section on the side of the first axis is installed on the cover rotatably about the second axis, the first housing has a first display unit that is provided on a first surface, the second housing has a second display unit that is provided on a second surface, the coupling unit couples the first and second housings (11, 21) so as to assume a first state in which the first surface and the second surface form substantially the same surface, and a second state in which the first surface and the second surface face in mutually opposing directions, the cover is provided with a first region and a second region, respectively on one side and the other side of the second axis, and in an open state of the cover, the first and second regions of the cover form substantially the same surface, in the first state, a rear surface of the second housing is covered by the first region of the cover which is in the open state, and in the second state, the first region of the cover which is in the open state covers the first surface of the first housing, or the second region of the cover which is in the open state covers the second surface of the second housing, wherein both ends of the first end section in the direction of extension of the second axis and both ends of the cover on the second axis are installed rotatably, wherein recess sections (42, 52) are formed in both ends of the first end section in the direction of extension of the second axis, projecting sections (42, 52) that couple rotatably with the recess sections (42, 52) are formed in both ends of the cover on the second axis, and wherein the recess sections (42, 52) are formed so as to extend in the thickness direction of the second housing. a portable terminal that is provided with a first housing, a second housing and a coupling unit that couples the first and second housings (11, 21) rotatably about a first axis; and a cover that covers at least a portion of the portable terminal and that is foldable about a second axis parallel to the first axis, wherein a first end section of the second housing on the side opposite to the end section on the side of the first axis is installed on the cover rotatably about the second axis, the first housing has a first display unit that is provided on a first surface, the second housing has a second display unit that is provided on a second surface, the coupling unit couples the first and second housings (11, 21) so as to assume a first state in which the first surface and the second surface form substantially the same surface, and a second state in which the first surface and the second surface face in mutually opposing directions, the cover is provided with a first region and a second region, respectively on one side and the other side of the second axis, and in an open state of the cover, the first and second regions of the cover form substantially the same surface, in the first state, a rear surface of the second housing is covered by the first region of the cover which is in the open state, and in the second state, the first region of the cover which is in the open state covers the first surface of the first housing, or the second region of the cover which is in the open state covers the second surface of the second housing, wherein both ends of the first end section in the direction of extension of the second axis and both ends of the cover on the second axis are installed rotatably, wherein recess sections (42, 52) are formed in both ends of the first end section in the direction of extension of the second axis, projecting sections (42, 52) that couple rotatably with the recess sections (42, 52) are formed in both ends of the cover on the second axis, and wherein the recess sections (42, 52) are formed so as to extend in the thickness direction of the second housing.