To provide a hinge device with an incorporated counter balance for working as a hinge, and capable of obtaining large torque, while restricting the friction torque small, and capable of restricting a difference between the swing torque in one direction and the swing torque in the other direction small.

A first frame 2 to be fitted to a casing and a second frame 6 to be fitted to an opening/closing cover are connected by a center shaft 10 freely to swing. The counter balance 15 is incorporated. The counter balance 15 is structured of compression coil springs 16 and guide members 20 and 17 for guiding the compression coil springs. The guide member is structured of the cylinder 20 and the sliding shaft 17 to be inserted into the cylinder 20 freely to be drawn. One of the coil springs 16 is received by a spring receiver part 21 unified with the cylinder 20, and the other thereof is received by a spring receiving bracket 26. The counter balance 15 formed into a unit is fitted to the predetermined position of the first and the second frames 2 and 6 freely to swing.