At a transfer electrode to which a normally low transfer pulse is applied, the time period in which the negative potential is applied is long, and an electric field is applied to a gate insulating film, such that the device's reliability decreases. To overcome this drawback, a negative side potential (VL′) of a normally low vertical transfer pulse (Vφ3, Vφ4) is set smaller in the absolute value than a negative side potential (VL) of a normally high vertical transfer pulse (Vφ1, Vφ2). Thereby, while the influence of increase in the dark current is being suppressed, the electric field being applied to the gate insulating film is reduced.