Abstract: An object of the present invention is to provide a plastic ampule capable of suppressing volatilization and scattering of a drug solution and elution of plastic compounding ingredients into the drug solution, as well as suppressing whisker formation and deformation and damage of an opening when the plastic ampule is opened. A plastic ampule 10 according to the present invention includes a drug solution storage part 11 for storing a drug solution, a drug solution discharge tube 12 in communication with the drug solution storage part 11 and extending toward one side, and a top part 13 closing an end at the one side of the drug solution discharge tube 12, and the drug solution discharge tube 12 includes a fragile part 14 formed to have a thin thickness along a circumferential direction.