To provide a storing case for a mask blank capable of suppressing adhesion of particles on the mask blank caused by dusting when a lid is opened and closed.

The storing case for the mask blank includes a case body 5 with an opened upper part and a lid body 6 for covering the case body 5, and stores the mask blank therein. A fixing member 8 covered from the upper part of the lid body 6 is engaged with the case body 5 at a position lower than a connecting part between the case body 5 and the lid body 6 when the lid body 6 is covered on the case body 5 to fix the lid body 6 and the case body 5.