A driving method of an imaging apparatus comprises: horizontally transferring, by a horizontal scanning circuit, a signal based on a photoelectric conversion portion of a first pixel unit held in a signal holding capacitor to a common line; before ending of the horizontal transfer; applying, by a reset switch of a second pixel unit, a selection reset voltage to a floating diffusion region of the second pixel unit; and after the horizontal transfer, transferring, by a transfer switch of the second pixel unit, a signal of a photoelectric conversion portion of the second pixel unit to the floating diffusion region of the second pixel unit and amplifying, by an amplification transistor of the second pixel unit, a signal of the floating diffusion region of the second pixel unit to output the signal to an output line.