A drug-filled synthetic resin ampule 1m includes an ampule main body 2m and a drug 6 stored in the ampule main body 2m. The ampule main body 2m includes a distal end portion 3, a hollow portion 21 having a drug storing portion 23, and an annular breakable portion 5 provided between a lower portion of the distal end portion 3 and an upper portion of the hollow portion 21. The ampule main body includes no inner surface protrusion on an inner lateral portion thereof which is located on a side toward the distal end portion with respect to the annular breakable portion. The distal end portion is configured such that an inner top surface of the distal end portion is located near a plane defined by the annular breakable portion and an inner surface of the distal end portion is a low-drug-retention surface.
