To provide a drug cartridge whose external shape in a state integrated with a drug bottle is simplified and whose operability can be improved while securing safety of a person engaged in drug preparation.

A drug cartridge 10 includes an outer wall part 21, a fixation part 23, a joint part 30, a vent needle part 31, and a sealed bag 24. The outer wall part 21 internally forms a retention space S1 internally having a drug bottle B. The fixation part 23 holds the drug bottle B loaded in the retention space S1. The joint part 30 leads a syringe needle part 11a to an opening part B4 of the drug bottle B. The vent needle part 31 is inserted into a rubber cap B3 mounted on the opening part B4 of the drug bottle B. The sealed bag 24 internally has a sealed space S2 communicating with the inside of the drug bottle B via the vent needle part 31 when the first edge of the vent needle part 31 is inserted into the drug bottle B.