An image synthesizing apparatus according to the present invention comprises coefficient setting means for setting a blending coefficient .alpha.(0.ltoreq..alpha..ltoreq.1) at a specified value when a value of a specific picture element component included in picture element components A of a first image is a predetermined value; and arithmetic means for performing an operation on the picture element components A, picture element components B of a second image, and the blending coefficient .alpha. as follows: A*.alpha.+B*(1-.alpha.), and performing the operation on all the picture element components A and the picture element components B of a picture element that has the specific picture element component representing the predetermined value by using the blending coefficient .alpha. set by the coefficient setting means.