Provided is an image sensor including a semiconductor substrate having first and second surfaces, transistors on the first surface, first and second lower pad electrodes apart from each other on a first interlayer insulating film covering the transistors, a mold insulating layer on the first and second lower pad electrodes, a first lower electrode inside a first opening passing through the mold insulating layer on the first lower pad electrode, a second lower electrode inside a second opening passing through the mold insulating layer on the second lower pad electrode, a dielectric film and an upper electrode on the first and second lower electrodes, a first contact plug passing through the mold insulating layer and connected to the first lower pad electrode, and a second contact plug passing through the mold insulating layer and connected to the second lower pad electrode.