An expansion valve device includes an electric driver having a stepping motor so as to control an opening degree of a refrigerant passage by displacing a valve member in accordance with a rotation angle of the stepping motor. A controller drives the stepping motor in a micro step when a flow rate of refrigerant flowing through the refrigerant passage is equal to or less than a predetermined value, and drives the stepping motor in a full step when the flow rate of the refrigerant is larger than the predetermined value.