A reference standard set for BNP measurement, including a plurality of reference standards including BNP-32 and proBNP, wherein the ratio BNP-32/proBNP (mole ratio) differs between the reference standards, and when a reference standard having a high mole ratio and a reference standard having a low mole ratio are compared, the BNP concentration, which is the sum total of the BNP-32 concentration and the proBNP concentration, is lower in the reference standard having a high mole ratio than in the reference standard having a low mole ratio. The present invention makes it possible to provide: a reference standard set for BNP measurement, whereby, when the BNP concentration value of a specimen measured by a certain BNP measurement method and the BNP concentration value of the specimen measured by another BNP measurement method are corrected using the reference standard set for BNP measurement, the corrected measurement values can be made to more closely coincide in comparison with a case in which the measurement values are corrected using a conventional reference standard; and a method for correcting, using the reference standard set for BNP measurement, the measured BNP concentration value of a specimen.