Abstract: A plastic ampule comprising a body portion, a head portion provided continuously to the mouth portion of the body portion through a cut-off portion, and a knob portion provided continuously to the head portion the ampule being unsealed by twisting the knob portion with fingers to cut the head portion off the mouth portion, wherein the hollow portion in the head portion is formed in the shape of a bowl. Since the hollow portion is formed in the shape of a bowl, content liquid remaining in the hollow portion can be discharged easily, the plastic ampule can be unsealed easily, and the content liquid remaining in the hollow portion is not scattered easily at the time of unsealing.