A valve characteristic controller including an oil pump, a valve timing varying mechanism, and a valve timing control unit is disclosed. The valve timing varying mechanism varies the valve characteristic value of intake valves in an engine based on the hydraulic pressure of hydraulic oil supplied from the oil pump. The valve timing control unit includes a storage and a detector. The storage stores computation maps used to calculate a target value for the valve characteristic value based on a plurality of engine control values. The detector detects the temperature of the hydraulic oil. The computation maps include a first map and a second map. The varying amount of the valve characteristic amount corresponding to a change in the engine control value in a low speed range of the engine speed is set to be smaller in the second map than the first map. The valve timing control unit switches the computation maps from the first map to the second map when the detected temperature of the hydraulic oil is relatively high.