PURPOSE: To obtain a noise interrupting cover capable of interrupting noises more securely, without taking much time at the time of manufacture, by forming its center board and side boards in the shape of a united body.

CONSTITUTION: The title noise interrupting cover is composed of a center board 2 arranged between a primary winding and a secondary winding, and upper and lower side boards 3a and 3b which are provided vertically to the board 2 and cover the sides of parts of the winding. And the center board 2 is made by folding back a copper board sheet and laminating it into a two-layer sheet, and has an opening 5 in the vicinity of its center part for inserting an iron core into. And a groove 6 is formed from the side of the opening 5 toward the external sides of the center board 2. Since the upper and lower side boards 3a and 3b are in the shape of a united body with the center board 2, the upper side boards 3a are bent upwards to a right angle, and the lower side boards 3b are similarly bent downwards to the right angle in case of manufacture. Accordingly, gap generation and peeling are prevented. Besides, the title noise interrupting cover can be manufactured without taking much time. And, it becomes possible to increase product accuracy and interrupt noises more securely.