A colorimetric blood glucose meter for measuring an absorbance of glucose contained in a sample, the colorimetric blood glucose meter comprising: a light source for emitting light having a wavelength to be absorbed by glucose, a first light-receiving element and a second light-receiving element for outputting signals corresponding to the intensity of received light; the first light-receiving element and the light source are arranged so that transmitted light emitted from the light source and passed through the sample is received by the first light-receiving element, the second light-receiving element is arranged to receive light other than the transmitted light emitted from the light source, wherein the colorimetric blood glucose meter further comprises a memory part, a driving part, an insertion hole with a limit switch, and a calculating part, said driving part being connected to said limit switch that is turned on when a sample is inserted into said insertion hole, wherein the driving part is configured to output a notification signal to the calculating part when the limit switch is turned on, and the calculating part is configured to instruct the driving part to allow the light source to emit light on reception of the notification signal, said memory part being arranged to store a proportionality constant t 1 that expresses a correlation between an output value of the first light-receiving element and an output value of the second light-receiving element when light is emitted from the light source in a state where the sample is not inserted, wherein the proportionality constant t 1 is defined by the Equation 1 below, where A 10 and B 10 denote respectively the output values of the first light-receiving element and the second light-receiving element when light is emitted from the light source in a state where the sample is not inserted, and said calculating part being arranged to calculate the absorbance S of glucose from the output values of the first light-receiving element and the second light-receiving element when light is emitted from the light source in a state where the sample is inserted, and from the proportionality constant t 1, the calculating part being arranged to calculate S on the basis of Equation 2 below, where A 1 and B 1 denote respectively the output values of the first light-receiving element and the second light-receiving element when light is emitted from the light source in a state where the sample is inserted: [Equation 1] t 1 = A 10 / B 10 [Equation 2] S = − log A 1 B 1 ⋅ t 1 a light source for emitting light having a wavelength to be absorbed by glucose, a first light-receiving element and a second light-receiving element for outputting signals corresponding to the intensity of received light; the first light-receiving element and the light source are arranged so that transmitted light emitted from the light source and passed through the sample is received by the first light-receiving element, the second light-receiving element is arranged to receive light other than the transmitted light emitted from the light source, wherein the colorimetric blood glucose meter further comprises a memory part, a driving part, an insertion hole with a limit switch, and a calculating part, said driving part being connected to said limit switch that is turned on when a sample is inserted into said insertion hole, wherein the driving part is configured to output a notification signal to the calculating part when the limit switch is turned on, and the calculating part is configured to instruct the driving part to allow the light source to emit light on reception of the notification signal, said memory part being arranged to store a proportionality constant t 1 that expresses a correlation between an output value of the first light-receiving element and an output value of the second light-receiving element when light is emitted from the light source in a state where the sample is not inserted, wherein the proportionality constant t 1 is defined by the Equation 1 below, where A 10 and B 10 denote respectively the output values of the first light-receiving element and the second light-receiving element when light is emitted from the light source in a state where the sample is not inserted, and said calculating part being arranged to calculate the absorbance S of glucose from the output values of the first light-receiving element and the second light-receiving element when light is emitted from the light source in a state where the sample is inserted, and from the proportionality constant t 1, the calculating part being arranged to calculate S on the basis of Equation 2 below, where A 1 and B 1 denote respectively the output values of the first light-receiving element and the second light-receiving element when light is emitted from the light source in a state where the sample is inserted: [Equation 1] t 1 = A 10 / B 10 [Equation 2] S = − log A 1 B 1 ⋅ t 1