The controller calculates white-detection parameters that form the narrowest range with the highest luminance under a condition that the accumulated values of the respective colors are not reduced to "0", sets the resulting parameter in the white-detection circuit, and based upon the accumulated values of the respective colors that are output when the white-detection parameters that form the narrowest range with the highest luminance under the condition that the accumulated values of the respective colors are not reduced to "0" have been preset in the white-detection circuit, calculates the gains of R and B of the white-balance adjusting circuit, and sets the resulting gains in the white-balance adjusting circuit.