An object of this invention is to provide a hinge device simple in structure, excellent is cost efficiency, and excellent in durability, and a cellular phone using the hinge device. To attain this object, the hinge device includes a tubular member 5, a catch 3 which includes engagement projected parts 38 each having a convex surface with a specified radius of curvature formed thereon, a energizing means 4, and a disk 2 which includes engagement recessed parts 32 engaged with the engagement projected parts in regions opposed to the engagement projected parts 32 of the catch, respectively, and which is rotatably connected with the catch, each of the engagement recessed parts 32 having concave surfaces with a radius of curvature larger than the radius of curvature of the engagement recessed parts formed thereon. An engagement state in which the engagement projected parts 38 are engaged with the respective engagement recessed parts 32 is maintained by an energizing force of an energizing unit to fix the cover body section, whereas the engagement state is released by opening and closing the cover body section against the energizing force.