A method of measuring a quantity of a substrate in a sample liquid by inserting a biosensor into a measuring device, the method comprising: providing the biosensor which includes: an insulating board; an electrode part which includes a counter electrode, a measuring electrode and a detecting electrode disposed on at least a part of the insulating board; a sample supplying path which supplies the sample liquid to the electrode part; and a reagent layer at least partially disposed in the sample supplying path; wherein the detecting electrode is the electrode disposed most downstream along the sample supplying path from an inlet of the path along a flow of the sample liquid; providing the measuring device which includes: a supporting section which detachably supports the biosensor; a connecting terminal which applies a voltage to the electrode part; and a driving power supply; applying the voltage to a first group including the counter electrode and the measuring electrode and a second group including the detecting electrode and one of the measuring electrode and the counter electrode by the driving power supply when the biosensor is inserted into the supporting section; determining whether a sufficient quantity of the sample liquid is supplied to the sample supplying path based on whether first electrical current from the first group and a second electrical current from the second group exceed respective predetermined thresholds; measuring an elapsed time between the first electrical current exceeding the threshold and the second electrical current exceeding the threshold; calculating the quantity of the substrate of the sample liquid based on an electrical current measured due to a voltage applied to the electrode part; if the elapsed time is within a predetermined time, compensating the calculated quantity of the substrate of the sample liquid based on the elapsed time. providing the biosensor which includes: an insulating board; an electrode part which includes a counter electrode, a measuring electrode and a detecting electrode disposed on at least a part of the insulating board; a sample supplying path which supplies the sample liquid to the electrode part; and a reagent layer at least partially disposed in the sample supplying path; wherein the detecting electrode is the electrode disposed most downstream along the sample supplying path from an inlet of the path along a flow of the sample liquid; an insulating board; an electrode part which includes a counter electrode, a measuring electrode and a detecting electrode disposed on at least a part of the insulating board; a sample supplying path which supplies the sample liquid to the electrode part; and a reagent layer at least partially disposed in the sample supplying path; providing the measuring device which includes: a supporting section which detachably supports the biosensor; a connecting terminal which applies a voltage to the electrode part; and a driving power supply; applying the voltage to a first group including the counter electrode and the measuring electrode and a second group including the detecting electrode and one of the measuring electrode and the counter electrode by the driving power supply when the biosensor is inserted into the supporting section; determining whether a sufficient quantity of the sample liquid is supplied to the sample supplying path based on whether first electrical current from the first group and a second electrical current from the second group exceed respective predetermined thresholds; a supporting section which detachably supports the biosensor; a connecting terminal which applies a voltage to the electrode part; and a driving power supply; applying the voltage to a first group including the counter electrode and the measuring electrode and a second group including the detecting electrode and one of the measuring electrode and the counter electrode by the driving power supply when the biosensor is inserted into the supporting section; determining whether a sufficient quantity of the sample liquid is supplied to the sample supplying path based on whether first electrical current from the first group and a second electrical current from the second group exceed respective predetermined thresholds; measuring an elapsed time between the first electrical current exceeding the threshold and the second electrical current exceeding the threshold; calculating the quantity of the substrate of the sample liquid based on an electrical current measured due to a voltage applied to the electrode part; if the elapsed time is within a predetermined time, compensating the calculated quantity of the substrate of the sample liquid based on the elapsed time.