An image processing apparatus comprises: at least one processor or circuit configured to perform the operations of following units: an obtaining unit configured to obtain a plurality of image signals being composed of image signals shot wider different shooting conditions; a determination unit configured to determine a composition rate in order to composite an image signal that has the predetermined shooting condition with a noise-reduced image that has the predetermined shooting condition, in accordance with an inter-frame change amount and a parameter indicating the predetermined shooting condition; a noise reduction unit configured to composite the image signal with the noise-reduced image using the composition rate to generate a new noise-reduced image; and a composition unit configured to composite the new noise-reduced image and an image signal that has another shooting condition.