Spectrum measuring device, spectrum measuring method, and specimen container

A spectral measurement apparatus for irradiating a sample as a measurement object with excitation light and detecting light to be measured, comprising:

• a light source configured to generate the excitation light;
• an integrator having an input opening portion for inputting the excitation light, and an output opening portion for outputting the light to be measured;
• a sample container made of a transparent material and including a housing portion defining a depressed portion for housing the sample and arranged in the integrator;
• an incidence optical system configured to irradiate the sample with the excitation light so that an irradiation area of the excitation light is set larger than an opening area of the depressed portion and the sample in the depressed portion;
• a photodetector configured to detect the light to be measured output from the output opening portion and to output a detection signal;
• and
• an analyzer configured to calculate a quantum yield of the sample, based on the detection signal.