A photoelectric conversion module has an optical element to transmit/receive optical signals, a stem to fix the optical element, a cap to cover the optical element, and a plurality of leads to impose electric signals to the optical element or to transmit electric signals from the optical element, wherein a flat section is disposed at an end of a predetermined lead located inside the package formed of a stem and the cap, and on the flat section, there is provided an electric circuit component one end of which is connected to the optical element and the other end of which is connected to the lead.