Provided is an optical transmission circuit capable of realizing a high-quality optical signal waveform with low power consumption. An optical transmission circuit (10) includes: a laser diode (800); a modulator (900) for supplying a differential modulation current to an anode terminal and a cathode terminal of the laser diode (800) through transmission lines (301 to 304); a current source (101) for supplying a forward bias current to the laser diode (800); and a magnetic sheet (wave absorber) (400) disposed so as to cover at least a part of the transmission lines (303 and 304). An impedance of the laser diode (800) is lower than characteristic impedances of the transmission lines (301 to 304) which are formed so that the characteristic impedances thereof are matched to an output impedance of the modulator (900).