A biosensor calibration method configured to measure a concentration of a specific substance contained in sample liquid to be measured, including: a first step configured to acquire a first output value that is output by the biosensor when first calibration liquid is brought into contact with the biosensor; a second step configured to acquire a second output value that is output by the biosensor when second calibration liquid having a different concentration from that of the first calibration liquid is continuously brought into contact with the biosensor after the first step and determine time for replacement of the biosensor on the basis of the first output value and the second output value.