PROBLEM TO BE SOLVED: To provide an optical measuring device that measures a wavelength by synchronizing a light measurement unit including a CCD operating at a predetermined exposure cycle with a light emission unit, and provide a wavelength measurement method of a light-emitting element.SOLUTION: An optical measuring device 1 comprises a signal generation unit 310 which, when a CCD 220 receives a first measurement trigger M1a in a first measurement period E1a, generates a voltage application trigger V1a at a first time of a second measurement period E2a, and generates a second measurement trigger M2a at a start time of a third measurement period E3a. Upon reception of the voltage application trigger V1a, a voltage application unit 130 starts to apply a voltage to a light-emitting element L1. Upon reception of the second measurement trigger M2a, the CCD 220 starts exposure and detects light in the third measurement period E3a. The first time of the second measurement period E2a is earlier than the start time
