Confocal measurement device

A confocal measurement device comprising:

• a light source that outputs white light to a first optical fiber cable;
• an optical coupler to which the first optical fiber cable, a second optical fiber cable, and a third optical fiber cable are connected;
• a sensor head that is connected to the second optical fiber cable, accommodates a diffraction lens causing a chromatic aberration in an optical-axis direction in incident white light, and applies light with a chromatic aberration caused therein to a measurement object;
• and
• a spectroscope that is connected to the third optical fiber cable, acquires reflected light which is reflected by the measurement object and collected by the sensor head via the second optical fiber cable, the optical coupler, and the third optical fiber cable, and measures a spectrum of the reflected light,
• wherein the optical coupler reduces a difference between an amount of light of a peak of a first transmission waveform and an amount of light of a peak of a second transmission waveform, wherein the first transmission waveform indicating a relationship between a wavelength and an amount of light when light is transmitted from the first optical fiber cable to the second optical fiber cable and the second transmission waveform indicating a relationship between a wavelength and an amount of light when light is transmitted from the second optical fiber cable to the third optical fiber cable, and the optical coupler is a filter type coupler or a spatial optical system type coupler.