PURPOSE: To reduce the breakage of a tape and to shield up the disturbance magnetism by having a contact between a conductive closure member and a conducting plate for short ring which covers a rotary magnetic head and forming a short ring of the different direction from the conducting plate.

CONSTITUTION: When a cassette 51 goes up toward an arrow B, a closed guard cover 51a touches a flat part 110a. Then the cover 51a is pushed to the closing direction (an arrow A) by means of an approximately hemispherical part 110b. When the cassette 51 rises up further, the cover 51a passes through the neutral point of a toggle mechanism and is closed completely. In such a way, it is possible to provide a guard cover closing mechanism to a cassette loading device with no use of a mobile part and with a single unit of member of an extremely simple form. Furthermore the disturbance of a screen due to an external harmful radio wave, i.e., a problem caused in a field use can be effectively eliminated since a shielding plate 120 and a chassis are grounded by a touch between the tip 110a and the plate 120.