A MOS type solid state imaging device having unit pixels, each having a photodiode a transfer transistor for transferring the signal of the photodiode to a floating node, an amplifier transistor for outputting the signal of the floating node to a vertical signal line, and a reset transistor for resetting the floating node. A gate voltage of the reset transistor is controlled by three values of a power source potential (for example 3V), a ground potential (0V), and a negative power source potential (for example −1V).