A liquid level detection device is provided with a fixed body and a rotating body, having a float and an arm. The arm has an insertion portion inserted into the rotating body and an extending portion extending straight and bent relative to the insertion portion. The rotating body has an insertion hole in which the insertion portion of the arm is inserted, a holding portion having a receiving opening receiving the extending portion and holding the extending portion received by the receiving opening, a stopper having an end face and releasing the receiving opening from a blocking state in which the end face blocks the receiving opening, and a protruding wall disposed on an opposite side to the holding portion with the stopper in between and protruding in the opposite direction beyond the end face in the blocking state.