To provide an optical power meter for speedily measuring the quantity of light.

The optical power meter comprises: a photo detector 1 for detecting light that is allowed to enter by an optical fiber; a light/voltage conversion means 2 for converting the output of the photo detector 1 to a specified voltage; an A/D converter 3 for converting the output voltage signal of the light/voltage conversion means 2 to digital data; a pulse detection means 4 for detecting the encoder pulse of a motor; a memory 5 for accumulating digital data converted by the A/D converter 3 and encoder pulses measured by the pulse detection means 4; a controller 6 for controlling the light/voltage conversion means 2, the A/D converter 3, the pulse detection means 4, and the memory 5; and a communication interface 7 for communicating with external equipment.