In a magnetic recording tape cassette comprising a bottom case, a top case assembled with the bottom case to provide a tape chamber, one or more of tape roll members mounted in the tape chamber in position, each of which includes a hub with a top projection for pivotting the hub and being mounted on the bottom wall of the bottom case and a magnetic recording tape wound on the hub, and a resilient spring member fixed to the undersurface of the top wall of the top case and having one or more of arms with the free ends thereof extending to the top projection of the corresponding hubs to resiliently rotatably support the hubs in position, the improvement comprises a recess defined in the undersurface of the top wall of the top case for accommodation of the fixed part of the spring member, said recess having a depth substantially equal to or larger than the thickness of the spring plate, said recess extending to at least a position corresponding to the maximum diameter of the tape roll member from the position where the spring plate is fixed.