A cassette 5 with longitudinal and transverse dimensions similar to each other is housed in a cassette storing case which can prevent housing of a cassette into the housing case in an incorrect direction and identify a dedicated cassette storing case corresponding to a cassette, while assuring the function of preventing positional shift during stacking. The cassette storing case 1 includes an indicating portion 15 provided on the top surface 1a of the housing case. The indicating portion 15 has a protrusion-and-recess pattern, similar to a design on the cassette, which indicates a housing direction. The cassette storing case 1 further includes a stopper portion 17, provided on the bottom surface 1b of the housing case, for engaging with part 16 of the indicating portion 15 to regulate positional shift when housing cases are stacked with each other.