A CCD image sensor is driven in an interlace scan method, in which readout of signal charge is performed in two divided fields. In the first field, signal charge Qs accumulated in photodiodes of the first horizontal line and noise charge Qn generated in VCCDs on the second horizontal line are transferred. In the second field, the signal charge Qs accumulated in the photodiodes of the second horizontal line and the noise charge Qn generated in the VCCDs on the first horizontal line are transferred. The image signal based on the noise charge Qn obtained in the second field is subtracted from the image signal Qs based on the signal charge obtained in the first field. Then the image signal based on the noise charge Qn obtained in the first field is subtracted from the image signal based on the signal charge Qs obtained in the second field.