This invention provides a substrate concentration measuring method for measuring a concentration of a substrate included in a specimen based on an output for measurement from an enzymatic electrode when the enzyme electrode and the substrate are reacted with each other, the substrate concentration is calculated using an output for correction from the enzymatic electrode obtained when a reference solution whose substrate concentration is known and the enzymatic electrode are reacted with each other before or after the enzymatic electrode and the substrate are reacted with each other. For example, the output for correction is measured by each specimen. In this method, the substrate concentration may be calculated using the output for correction for the specimen to be measured and an output for correction corresponding to at least one other specimen and measured prior to the output for correction.
