A measuring apparatus is provided with a light source (4), a first light-receiving element (5) and a second light-receiving element (6) which output signals corresponding to light intensity, a calculating part (12) and a memory part (13). The first light-receiving element (6) and the light source (4) are arranged so that transmitted light emitted from the light source and passed through a sample is received by the first light-receiving element (5). The second light-receiving element (6) is arranged so as to receive light other than the transmitted light emitted from the light source (4). In the memory part (13), a correlation between the output value of the first light-receiving element (5) and the output value of the second light-receiving element (6) when light is emitted from the light source (4) in a state where the sample is not present is stored. The calculating part calculates absorbance of a target component contained in the sample, from the output values of the first light-receiving element (5) and the second light-receiving element (6) when light is emitted from the light resource (4) in the state where the sample present, and from the correlation.