A valve device including a housing formed with a passage, valve elements for opening and closing the passage, a spring for urging the valve elements, and a controller for displacing the valve elements against the spring force. The spring has at least two deflection modes, one of which shows a larger spring constant than the other deflection mode and appears in one of two valve positions. The controller outputs a relatively large force for displacing the valve elements to the valve position at which the spring is deflected at the larger spring constant.