A hinge device for opening and closing a cover of office equipment, comprising: a housing which is disposed at a main body of an office equipment and having a pair of hinge holes on the upper portion thereof; a rotational lever which is fixedly disposed at a cover and having hinge holes at the rear thereof and being provided with a hinge connection part inserted into the upper portion inside the housing at the lower portion of the rear thereof; a hinge shaft being inserted into the hinge holes of the housing and the hinge holes of the rotational lever and combined with them and supporting rotation of the rotational lever and the cover; a compression coil spring being disposed inside the housing; and a slider being disposed on the upper portion inside the housing and being elastically supported by the compression coil spring, and the upper end portion of which contacts with the lower end surface of the hinge connection part of the rotational lever; wherein the hinge connection part of the rotational lever is located at the front of hinge holes, so that a multi-layered cam is provided to the lower end surface of the hinge connection part and a supporting surface is formed on the upper end surface of the slider, the multi-layered cam of the rotational lever has a stop cam in the center and at both sides thereof, down cams which locate at the rear than the surface of the stop cam and are lower than the stop cam, the supporting surface of the slider has an inclined plane that is getting higher toward the front, at the center of the front end, a stop surface which contacts with the stop cam of the rotational lever and down surfaces which is protruded from both sides of the stop surface and contact with the down cams are provided. a housing which is disposed at a main body of an office equipment and having a pair of hinge holes on the upper portion thereof; a rotational lever which is fixedly disposed at a cover and having hinge holes at the rear thereof and being provided with a hinge connection part inserted into the upper portion inside the housing at the lower portion of the rear thereof; a hinge shaft being inserted into the hinge holes of the housing and the hinge holes of the rotational lever and combined with them and supporting rotation of the rotational lever and the cover; a compression coil spring being disposed inside the housing; and a slider being disposed on the upper portion inside the housing and being elastically supported by the compression coil spring, and the upper end portion of which contacts with the lower end surface of the hinge connection part of the rotational lever; wherein the hinge connection part of the rotational lever is located at the front of hinge holes, so that a multi-layered cam is provided to the lower end surface of the hinge connection part and a supporting surface is formed on the upper end surface of the slider, the multi-layered cam of the rotational lever has a stop cam in the center and at both sides thereof, down cams which locate at the rear than the surface of the stop cam and are lower than the stop cam, the supporting surface of the slider has an inclined plane that is getting higher toward the front, at the center of the front end, a stop surface which contacts with the stop cam of the rotational lever and down surfaces which is protruded from both sides of the stop surface and contact with the down cams are provided.