Solid-state image pickup device and control method thereof

An image sensor controls the gain of a pixel signal on a pixel-by-pixel basis and extends a dynamic range while maintaining a S/N ratio at a favorable level. A column unit in an image sensor is independently detects a level of each pixel signal and independently sets a gain for level of the signal. A photoelectric converting region unit has pixels arranged two-dimensionally with a vertical signal line for each pixel column to output each pixel signal. The column unit is on an output side of the vertical signal line. The column unit for each pixel column has a pixel signal level detecting circuit, a programmable gain control, a sample and hold (S/H) circuit. Gain correction is performed according to a result of a detected level of the pixel signal.