Provided are an image sensor and a method for manufacturing the same. The image sensor comprises: a readout circuitry, an interconnection, a contact plug, and an image sensing device. The readout circuitry is formed in a first substrate. The interconnection is electrically connected to the readout circuitry over the first substrate. The contact plug is formed over the interconnection, and includes an insulating layer at regions in an upper side thereof. The image sensing device is formed over the contact plug.