To provide an aircraft use water heater that operates by an aircraft power source of an AC variable frequency mounted in an aircraft, that is small, light-weight, safe, and low power consumption, and that can supply warm water stably. In an aircraft use water heater composed of a tank section for heating liquid stored therein and a controlling section for controlling the heating of the liquid by an aircraft power source, a bottom face of the tank section has a baffle plate and, liquid flowing in the tank section collides against the baffle plate to flow in a different direction parallel to the bottom face and is upwardly moved, while being heated, in the vicinity of a helical coil-type heater and is taken out through a liquid outlet.
