To attach a GPS antenna detachably to the screen panel of a personal computer and to easily prescribe the horizontal surface by allowing a base to rotate on a shaft body supported by a clip and mounting the GPS antenna on the base.

A rectangular recessed part is formed in the base 22 and an iron plate 33B is mounted there. This iron plate 33B is for the attraction of a magnet for antenna fitting provided to the lower part of the GPS antenna. A bearing part 33C is formed below the base 33 and the shaft body 32 penetrates it. The shaft body 32 united with the base 33 is inserted into a couple of semicylindrical recessed parts of the clip 31 and its rotational position to the clip 31 can be adjusted manually with torque of rotation making good use of the elasticity of a spring 31C and the friction of the raw material. This torque of rotation has a retaining force for holding a horizontal position even when the GPS antenna is mounted on the base 33, but when a force is applied by manual operation to some extent, the antenna rotates to vary the angle of the base 33.