A fiber optic module includes a connector connected to a mother board of a host computer, an LD semiconductor IC for converting serial data received from the mother board to an LD electric signal for a laser diode, an LD module for converting the LD electric signal to an LD optical signal, a PD module for converting a photodiode optical signal to a PD electric signal, a PD semiconductor IC for converting the PD electric signal to PD serial data, a circuit board having the connector and carrying LD semiconductor IC and PD semiconductor IC, an LD shielding plate and a PD shielding plate for electrically shielding the LD module and the PD module, respectively a .[.first frame and a second.]. frame for holding the circuit board, LD module and PD module. In the fiber optic module, the connector is of a surface mounting type, leads of the LD and PD modules are connected to a side of the circuit board mounted with the connector, the circuit board has an LD variable resistor for adjusting a drive current of the LD module, the LD variable resistor is provided to a side of the circuit board opposite to the connector, the circuit board has a PD variable resistor provided to the side of the circuit board opposite to the connector for detecting a signal of the PD module, 3 signal processing semiconductor ICs or less are provided.