According to one embodiment, an optical coupling device is provided.A first photodiode receives an optical signal generated by a light emitting element and converts the optical signal into a first electrical signal. A first inverting amplifier is provided with a first feedback resistor and a first operating amplifier connected in parallel with each other. The input end is connected to a cathode of the first photodiode. A first signal which is obtained by inverting the first electrical signal is output from the output end. A second inverting amplifier is provided with a second feedback resistor and a second operating amplifier connected in parallel with each other. The input end of the second inverting amplifier is connected to a cathode of a second photodiode. The second inverting amplifier outputs a second signal from the output end. A comparator receives the first and second signals and outputs a comparison amplified signal.