Abstract: An air conditioner for use with a car employing a sunshine sensor having three light receiving elements. A first light receiving element faces upward and a second light receiving element and a third light receiving element are inclined toward a front side by an identical angle along an advancing direction of the car and are symmetrically inclined with respect the car advancing direction along a horizontal direction vertical to the car advancing direction. The inclination is determined such that a vector obtained by adding normal vectors respectively of light receiving surfaces of the light receiving elements has a direction substantially identical to a direction of sunshine which maximizes a quantity of heat supplied from the sunshine to the car. Outputs from the first, second, and third light receiving elements are added to each other to obtain a sunshine intensity.