To provide an auto white balance apparatus and a white balance adjusting method capable of performing more stable white balance adjustment. For every block, a characteristic pixel determination circuit 106 determines a characteristic pixel from among a pixel group in a block and a light-source reflection determination circuit 108 determines whether the typical value of a block reflects the light source of an input image, by comparing the color difference of a characteristic pixel of the block with the typical color difference of the block. Then, as a result of the determination, a white balance evaluating circuit 110 determines the light source of an image by using blocks that reflect the light source.