To provide a method for measuring the concentration of ethanol in an aqueous sample which can be implemented by a simple apparatus requiring relatively simple operation.

A calibration data for correlating (a) a plurality of transmission quantities of a plurality of calibration samples in a drink containing ethanol of different known concentration measured, as a plurality of transmission quantities of electromagnetic wave in near infrared region, at such eigen wavelength as the electromagnetic wave is relatively opaque but transparent for ethanol with (b) known concentration of ethanol in a plurality of calibration samples. At least one light transmission quantity is measured for a test sample at an eigen wavelength prevailing when the calibration data is determined. Finally, at least one light transmission quantity of a test sample is converted into a designated concentration of ethanol in test sample according to a relationship determined by the calibration data.