A medical device includes a connector portion. The connector portion includes an inner cylinder connectable to another medical device having an elastic valve, a valve body against which the elastic valve is pressed from a distal end side due to connection of the inner cylinder and another medical device, and an outer cylinder disposed radially outside the inner cylinder, and the connector portion is configured to provide fluid communication between the connector portion and another medical device by moving the inner cylinder in an axial direction with respect to the outer cylinder in a state where the inner cylinder is connected with another medical device. The connector portion further includes an anchor that suppresses movement of the valve body with respect to the inner cylinder toward a proximal end.