An aircraft use water heater comprising a tank section for heating liquid stored therein and a controlling section for controlling the heating of the liquid by an aircraft power source, wherein the aircraft use water heater includes: an inflow inlet formed in a bottom face of the tank section through which the liquid flows into the tank section; a baffle plate that is provided at an upper part of the inflow inlet and that prevents the liquid from moving in a straight manner; a helical coil-type heater in the tank section, the helical coil-type heater has a helical axis provided in a direction parallel to the bottom face of the tank section; and a liquid outlet formed in an upper part of a wall face of the tank section, liquid flowing from the inflow inlet to the tank section collides against the baffle plate to flow in a different direction parallel to the bottom face of the tank section and moves to the lower part of the helical coil-type heater and then is moved upwardly, while being heated, in the vicinity of a helical coil section of the helical coil-type heater and the heated liquid is caused to flow through the liquid outlet, characterised in that the baffle plate is provided in a direction dislocated by a predetermined angle from a direction along which the baffle plate is orthogonal to a helical axis of the helical coil-type heater, liquid flowing from the baffle plate in a direction parallel to the bottom face collides against a helical coil section at a lower part of the helical coil-type heater to flow in a different direction and is moved upwardly, while being heated, in the vicinity of the helical coil section, and in that the baffle plate is composed of an upper face plate against which water flowing from the inflow inlet to the tank section collides, side face plates covering side faces other than that in the direction along which water flows out and a connecting section for connecting the baffle plate to the tank bottom face. an inflow inlet formed in a bottom face of the tank section through which the liquid flows into the tank section; a baffle plate that is provided at an upper part of the inflow inlet and that prevents the liquid from moving in a straight manner; a helical coil-type heater in the tank section, the helical coil-type heater has a helical axis provided in a direction parallel to the bottom face of the tank section; and a liquid outlet formed in an upper part of a wall face of the tank section, liquid flowing from the inflow inlet to the tank section collides against the baffle plate to flow in a different direction parallel to the bottom face of the tank section and moves to the lower part of the helical coil-type heater and then is moved upwardly, while being heated, in the vicinity of a helical coil section of the helical coil-type heater and the heated liquid is caused to flow through the liquid outlet, characterised in that the baffle plate is provided in a direction dislocated by a predetermined angle from a direction along which the baffle plate is orthogonal to a helical axis of the helical coil-type heater, liquid flowing from the baffle plate in a direction parallel to the bottom face collides against a helical coil section at a lower part of the helical coil-type heater to flow in a different direction and is moved upwardly, while being heated, in the vicinity of the helical coil section, and in that the baffle plate is composed of an upper face plate against which water flowing from the inflow inlet to the tank section collides, side face plates covering side faces other than that in the direction along which water flows out and a connecting section for connecting the baffle plate to the tank bottom face.