A double-use nozzle adapter includes a main body, a switch unit, and a needle unit. The switch unit includes a shifting member and two rigid retaining members. The rigid retaining members are arranged between the shifting member and the main body. The shifting member shifts the rigid retaining member between a first position and a second position. The needle unit is slidably installed in the main body and includes a needle. In the first position, the shifting member drives the rigid retaining member to press against the needle, thereby preventing the needle from moving with respect to the main body and making the needle connectable to a Schrader valve. In the second position, the rigid retaining member moves between the shifting member and the main body, so as to allow the needle to move with respect to the main body and make the needle connectable to a Presta valve.