A sensor frame for an image sensor is manufactured in the step of forming a sensor frame for an image sensor by extrusion molding so that a frame support portion for supporting the frame is formed above a lens array holding portion, and the step of removing the thus-formed sensor frame support portion by machining while leaving parts of the support portion located at the longitudinally corresponding to the upper ends of the lens array holding portion. Accordingly, machined surfaces subjected to the machining exist outside the hollow space where the sensor ICs are located.