To provide a hinge device which is used for an opening/closing mechanism of a portable telephone or the like, which enables a box body to be opened at a wide angle, which can be miniaturized, and which is also excellent in durability.

The hinge device has a first cam 12, a second cam 14, and axial bodies 4, 116. The first cam 12 is engaged with a cylindrical member with flexible sliding, and an engagement protrusion 38, a first recess 40 and a second recess 42 are each formed on the cam surface of the hollow base part of the first cam 12. The second cam 14 is brought into cam engagement face to face with the first cam by an energizing means 10, and an engagement protrusion 58, a first recess 60 and a second recess 62 are each formed on the second cam 14. The engagement protrusion of the first cam and the engagement protrusion of the second cam are engaged with the first recess of the second cam and the first recess of the first cam respectively in the closed position of the opening/closing box body. On the other hand, the engagement protrusion of the first cam and the engagement protrusion of the second cam are engaged with the second recess of the second cam and the second recess of the first cam respectively in the maximum open position of the opening/closing box body. Thus, the opening/closing box body can be retained.