We report two cases of intestinal perforation caused by accidental swallowing of Press-Through Packages (PTP). The first case occurred in a 90-year-old woman with moderate dementia. She was admitted to our hospital because of abdominal pain and intestinal obstruction. She showed symptoms and sign of peritonitis and underwent abdominal surgery. The postoperative diagnosis was diffuse peritonitis due to a perforated rectal ulcer caused by the sharp corners of an accidentally swallowed PTP. The second case occurred in an 82-year-old woman with recurrent symptoms and signs of intestinal obstruction. She underwent abdominal surgery and the operation revealed an ileal perforation due to penetration by the sharp edge of a PTP. Both patients were discharged in good condition. PTPs are rapidly becoming popular as packaging for tablets and capsules. However, reports of accidental swallowing of PTPs have recently been increasing. In most cases, the PTPs were found in the esophagus and removed endoscopically. Progression of accidentally swallowed PTPs to the intestines is rare. However, when this occurs, the patient's condition becomes more serious. We propose that drugs should not be dispensed in PTPs but rather handed to the patients, especially to elderly patients, or when impossible, the corners of PTPs should be rounded.