The present invention provides an encoder which comprises an input portion configured to be input an encoding target image acquired from an image capturing portion, wherein the encoder is arranged to divide the encoding target image into coding units, the coding units including an encoding block of a luma signal and an encoding block of a chroma signal; to acquire characteristics of chroma components of the encoding target image; and to further divide the encoding block of the luma signal and the encoding block of the chroma signal into encoding blocks of a same division structure or different division structures, in accordance with the acquired shooting condition.