A vial adapter is provided with a fitting portion which can be fitted into the head portion of a vial, and a hollow needle with a side hole. The base end portion of the needle is provided with a stopper contact portion which contacts the top surface of a stopper when the fitting portion is fitted in the head portion of the vial. When the fitting portion is fitted in the head portion of the vial, the stopper contact portion contacts the top surface of the stopper, and the fitting portion is fixed to the head portion of the vial by a claw engaging with the head portion of the vial, and further, the region of the side hole nearest the base end portion of the needle is positioned either roughly at the bottom surface of the stopper or inside of the stopper.
