The optical filter of the present invention is provided with a near infrared light absorption layer that contains a component composed of copper ions and a phosphoric ester compound expressed by the following Formula (10), in which the phosphorus atom content in the near infrared light absorption layer is 0.4 to 1.3 mol per mole of copper ions, and the copper ion content in the near infrared light absorption layer is 2 to 60 wt %. Thus keeping the phosphorus atom and copper ion content within specific ranges results in good near infrared light absorption and in improved moisture resistance whereby devitrification caused by whitening is suppressed ##STR1##