PURPOSE: To hardly allow a secular change by constituting a film pressing member out of a plastic material having a glass transition point of more than a specific temp.

CONSTITUTION: A 3.5 inch diskette or a microdiskette is composed of a bottom housing part 1, a lid housing part 2, a magnetic disk 3, small components consisting of a slide 4 and a slide closing spring 5, a lift member 6 and a write protective member 7. The magnetic disk 3 has a hub 8 connected with the disk in the middle. A central part of the hub 8 is fitted with its outer circumferential edge part into a central opening hole part of the bottom housing part 1, so that the fitted magnetic disk 3 can be rotated in the housing parts 1 and 2. In this containers for magnetic recording medium, the film pressing member 6 is constituted of a plastic material (excluding polycarbonate) having a glass transition point of ≥80°C.