A signal read-out apparatus for a solid-state imager employing CCDs (charge-coupled devices) and CPDs (charge priming devices) includes a clamp circuit for eliminating reset noise generated in an amplifier provided at the output of the imager. For eliminating thermal noise of high frequency generated in the amplifier and incapable of being eliminated by the clamp circuit, a low-pass filter is provided in precedence to the clamp circuit. The frequency band of the low-pass filter is not higher than 1.5 times the frequency of a clock pulse signal for driving the solid-state imager. In place of providing the low-pass filter as a discrete component, a low-pass filter having the same characteristics may be constituted by a capacitance of the capacitor and ON-resistance of a switch incorporated in the clamp circuit. The capacitance of the capacitor in the clamp circuit is set to a value greater than the input electrostatic capacity of the amplifier.