The image sensing device includes a pixel region in a pixel array area and a dummy pixel region in a periphery area. The pixel region includes a radiation region, a floating diffusion region, a transfer transistor, a source-follower transistor, a reset transistor and a select transistor. The dummy pixel region includes a radiation region and a floating diffusion region. A gate of one of the transfer transistor, the reset transistor and the select transistor in the pixel region is electrically connected to the radiation region or the floating diffusion region in the dummy pixel region.