Measurement method and measurement device

A measurement method, comprising:

• preparing a first reacting substance and a second reacting substance, the first reacting substance having a higher reactivity to a second detection target than to a first detection target, the second reacting substance having a higher reactivity to the first detection target than to the second detection target, wherein the first detection target comprises a first disease-associated proteinaceous substance and the second detection target comprises a second disease-associated proteinaceous substance;
• preparing a sample;
• making the sample contact with the first reacting substance and the second reacting substance;
• measuring a first signal value of a first reaction between the first reacting substance and the sample, and a second signal value of a second reaction between the second reacting substance and the sample;
• and
• calculating a relationship between the first detection target and the second detection target in the sample based on a calibration curve which is prepared in advance, the first signal value, and the second signal value, wherein the calibration curve is prepared in advance based on a first reference signal value and a second reference signal value, the first reference signal value being based on a reaction between the first reacting substance and at least one reference sample having known concentrations of the first and second detection targets, and the second reference signal value being based on a reaction between the second reacting substance and the at least one reference sample.