signal charges are photoelectrically generated by a plurality of photodiodes , transferred through a transfer register to a charge detection capacitance and sensed through a floating junction , as a potential change of the charge detection capacitance to be amplified and output at an output amplifier composed of a plurality of stages of driver transistors , in which a field insulation film of a first stage driver transistor is formed , under a gate electrode , with a trapezoidal region left so that the gate electrode has a width thereof varied to be wider at a source end than at a drain end , permitting an increased reduction of the charge detection capacitance .