To install a personal computer on an existing desk which is not made exclusively for personal computers, and to utilize a surface of a desk fully without placing a main body of the personal computer thereon when the personal computer is installed.

A U-shaped, hooking device 9 comprised of an upper side part 6, a back side part 7, and a lower side part 8 is provided. A monitor 11 is equipped on the upper side part 7, and a case 16 to accommodate the main body of the personal computer is equipped on the lower side part. The upper side part 6 is hooked on the side of a top plate 2 of a table. The monitor 11 is placed on the desk, and the case 16 is placed in a space under the top plate 2.