PROBLEM TO BE SOLVED: To provide a PTP sheet package capable of safely storing medicine such as a tablet stored in a PTP sheet, and preventing unintended take-out of the tablet with a simple step.SOLUTION: A mount formation piece 12 to be fitted to a PTP sheet 36 comprises: a first side surface 14 overlapped to a surface of a flange part 38b on a projection part 38a side of the PTP sheet 36 and a second side surface 24 provided continuous to the first side surface 14 via a folding rule, and is overlapped to a surface on an opposite side of the flange part 38b. The first side surface 14 has a hole part 16 into which the projection part 38a is inserted. The second side surface 24 has a cover part 28 on a part opposed to an opening of the projection part 38a. The cover part 28 has a cover part half-cut line 32 formed of a half-cut line for cutting a part of thickness of the mount formation piece 12 on a surface 12a which is outside when the PTP sheet 36 is packed, and a hole part half-cut line 34 formed of a half-cut line along the vicinity of the cover part half-cut line 32 on a rear surface 12b of the mount formation piece 12.
