Abstract: A case for mounting on a probe of a radiation clinical thermometer a sheet shaped probe cover which includes a probe insertion member having an insertion opening to be inserted by the probe and an infection preventing sheet in contact with the probe insertion member. The case includes a cover storage portion for storing a series of continuing probe covers each having an engagement opening at a predetermined position thereof, a probe insertion cut portion for positioning each probe cover and for insertion by the probe, a support surface disposed around the probe insertion cut portion to support a peripheral of the insertion opening of the probe insertion member of one of the probe covers, and a projection adapted to be engaged with the engagement opening of a subsequent probe cover when the probe cover mounted on the probe is torn at the probe insertion cut portion.