PROBLEM TO BE SOLVED: To provide a measuring apparatus and a measuring method capable of chronologically and automatically measuring a concentration of an object substance with excellent reliability in the measuring apparatus and the measuring method for calculating the concentration of the object substance in biological fluid based on a current value measured.SOLUTION: A measuring apparatus 101 comprises: a voltage application section 400A continuously applying a voltage to a system including a first substance and a second substance generated by enzyme reaction from the first substance； a detection section 300 detecting a first current value measured by applying a first voltage as the voltage thereto and a second current value measured by switching the first voltage to a second voltage； a first arithmetic section computing a difference (ΔI) between the first current value and the second current value； a storage section 261 storing an analytical curve of the difference (ΔI) and a concentration of the first substance； and a second arithmetic section evaluating the concentration of the first substance from the difference (ΔI) and the analytical curve.SELECTED DRAWING: Figure 7【課題】体液中の被対象物質の濃度を、測定された電流値に基づいて算出する測定装置および測定方法において、優れた信頼性で被対象物質の濃度を経時的かつ自動的に測定することができる測定装置および測定方法を提供すること。【解決手段】本発明の測定装置１０１は、第１の物質と、前記第１の物質から酵素反応によって発生する第２の物質とを含む系に電圧を連続的に印加する電圧印加部４００Ａと、電圧として第１電圧を印加して測定される第１電流値と、第２電圧へ切り換えて測定される第２電流値とを検出する検出部３００と、第１電流値と第２電流値との差（ΔＩ）を演算する第１演算部と、前記差（ΔＩ）と、第１の物質の濃度との検量線を記憶する記憶部２６１と、前記差（ΔＩ）と検量線とから前記第１の物質の濃度を導く第２演算部とを備える。【選択図】図７
