The present invention relates to a substrate stacked image sensor having a dual detection function, in which when first to fourth photodiodes are formed in a first substrate, a fifth photodiode is formed in a second substrate, and the substrates are stacked and combined with each other, the first to fourth photodiodes and the fifth photodiode are combined with each other to obtain a complete photodiode as an element of one pixel, and signals individually detected in each photodiode are selectively read or added to be read according to necessity. To this end, the first to fourth photodiodes are formed in the first substrate, the fifth photodiode is formed in the second substrate, the first to fourth photodiodes and the fifth photodiode make electrical contact with each other, and pixel array sizes of the first substrate and the second substrate are allowed to be different from each other, so that sensor resolution of the first substrate and sensor resolution of the second substrate are different from each other.