To provide a fraudulent unsealing preventing plastic bottle containing a content for medical use strictly limited in usage or to be prevented form being drunk by a child, which cannot be unsealed easily.

The fraudulent unsealing preventing bottle with a cap comprises a bottle body (A) composed of a neck (1), a shoulder (2) continuous with the neck (1), a trunk (3) continuous with the shoulder (2), and a bottom (4) continuous with the trunk (3), and a cap body (B). After forming the bottle body (A), the neck (1) of the bottle body (A) is caved in to make the unsealing of the cap body (B) difficult.