PROBLEM TO BE SOLVED: To provide an adapter detection device for detecting an adapter, and prevent aging degradation caused by contact between a button and a sensor related to an injection device including the adapter detection device.SOLUTION: An injection device 1 for injecting medical solution includes: an injection head 2 on which a syringe filled with the medical solution is placed an adapter in which the syringe is placed on the injection head 2 and has protrusions and an adapter detection part 6 including buttons that are depressed by protrusions, and a sensor for contactlessly detecting the depression of the buttons.
