PURPOSE: To reduce cost and labor for manufacture by increasing the mounting area of the printed-circuit board of a high-frequency amplifier for miniaturization and reducing the number of used screws.

CONSTITUTION: A printed-circuit board 5 is held between a shield plate 7 and a base 3, and screws 2 are inserted from the bottom surface of the base to fix the shield plate by the screws. The printed board with a transistor 4 is fixed together with the shield plate and the base by the screws 2. The printed- circuit board dispenses with a screw for fixing the printed board to the shield board, thereby being able to increase a mounting area, so that when the mounting area is same, the miniaturization may be achieved. Since the thickness of the shield plate is sufficient if it can be fixed by a screw, it can be made thinner. Thereby, the increase of the mounting area and the miniaturization can be achieved and the number of used screws can be reduced, so that the cost and labor for manufacture my be reduced.