An electric equipment unit is mounted to a mount opening as in an instrument panel. The unit has on top a panel-connecting means electrically connected with its internal circuit, and on opposite left and right sides at an upper portion thereof clamps and at a lower portion thereof support shaft means. The mount opening has on its upper inner surface a unit-connecting means, on opposite left and right inner surfaces at an upper portion thereof fixing holes and at a lower portion thereof shaft-receiving means. The unit is rotated and mounted to the mount opening, with its support shaft means engaged in the mount opening shaft-receiving means, so that the clamps fit in the fixing holes, while at the same time the panel-connecting means is contacted and electrically connected with the unit-connecting means. The mountability of an electric equipment unit to a structure such as an instrument panel is so improved as to enable easy blind operation, while making it possible to attain the mounting and the electric connection at one time.