Provided is an image sensor. According to embodiments, the subject image sensor can include a photodiode for converting incident light into electrical signals, a reset transistor for resetting a voltage value of a unit pixel, a drive transistor for providing an output voltage, a select transistor for selecting the unit pixel, a storage capacitor for storing electrons leaking from the photodiode, and a switching transistor for controlling the flow of charge to and from the storage capacitor. The switching transistor can be disposed connected to a node between the photodiode and the reset transistor, and the storage capacitor can be disposed at a side of the switching transistor.