A measuring method for analytes using a sensor which is formed with a container comprising a sample-holding unit (104, 204, 304), a sample-supplying port (101, 201, 301) for supplying a sample to said sample-holding unit, and an opening (102, 202, 302), wherein: said sample-holding unit holds a sample including a first analyte and a second analyte, said sample-supplying port is provided at the end of said container, said first analyte is composed of an antigen comprising one of albumin, hCG, LH, CRP and IgG, said second analyte is composed of an ion comprising one of sodium ion, potassium ion, lithium ion, magnesium ion, calcium ion, chloride ion, ammonium ion, and hydrogen ion, said sensor further comprising a detecting unit (603; 111, 211, 311) for carrying out an electrochemical measurement, the detecting unit being provided in said sample-holding unit; a light-entrance unit (109, 308) for introducing incident light to said sample-holding unit, the light-entrance unit being provided in said sample-holding unit; a light-exit unit (110, 309) for releasing outgoing light from inside said sample-holding unit to outside said sample-holding unit, the light-exit unit being provided in said sample-holding unit; and a reagent-holding unit (108, 208, 307) for holding a reagent for performing an optical measurement, the reagent-holding unit being provided in said sample-holding unit; wherein in a flowing direction of said sample supplied from said sample-supplying port (101, 201, 301) in said sample-holding unit, said sample-supplying port, said detecting unit, and said reagent-holding unit are positioned in the order recited; the method comprising the steps of: supplying said sample to said sample-holding unit by suction; applying a voltage to said detecting unit; measuring an electric-signal from said detecting unit; quantifying said second analyte based on said electric-signal measured in said step; applying incident light to said sample held in said sample-holding unit via said light-entrance unit; performing an optical measurement by measuring outgoing light released from inside said sample-holding unit to outside said sample-holding unit via said light-exit unit, caused by the application of said incident light; and quantifying said first analyte based on said outgoing light measured in said step. said sample-holding unit holds a sample including a first analyte and a second analyte, said sample-supplying port is provided at the end of said container, said first analyte is composed of an antigen comprising one of albumin, hCG, LH, CRP and IgG, said second analyte is composed of an ion comprising one of sodium ion, potassium ion, lithium ion, magnesium ion, calcium ion, chloride ion, ammonium ion, and hydrogen ion, said sensor further comprising a detecting unit (603; 111, 211, 311) for carrying out an electrochemical measurement, the detecting unit being provided in said sample-holding unit; a light-entrance unit (109, 308) for introducing incident light to said sample-holding unit, the light-entrance unit being provided in said sample-holding unit; a light-exit unit (110, 309) for releasing outgoing light from inside said sample-holding unit to outside said sample-holding unit, the light-exit unit being provided in said sample-holding unit; and a reagent-holding unit (108, 208, 307) for holding a reagent for performing an optical measurement, the reagent-holding unit being provided in said sample-holding unit; wherein in a flowing direction of said sample supplied from said sample-supplying port (101, 201, 301) in said sample-holding unit, said sample-supplying port, said detecting unit, and said reagent-holding unit are positioned in the order recited; the method comprising the steps of: supplying said sample to said sample-holding unit by suction; applying a voltage to said detecting unit; measuring an electric-signal from said detecting unit; quantifying said second analyte based on said electric-signal measured in said step; applying incident light to said sample held in said sample-holding unit via said light-entrance unit; performing an optical measurement by measuring outgoing light released from inside said sample-holding unit to outside said sample-holding unit via said light-exit unit, caused by the application of said incident light; and quantifying said first analyte based on said outgoing light measured in said step. supplying said sample to said sample-holding unit by suction; applying a voltage to said detecting unit; measuring an electric-signal from said detecting unit; quantifying said second analyte based on said electric-signal measured in said step; applying incident light to said sample held in said sample-holding unit via said light-entrance unit; performing an optical measurement by measuring outgoing light released from inside said sample-holding unit to outside said sample-holding unit via said light-exit unit, caused by the application of said incident light; and quantifying said first analyte based on said outgoing light measured in said step.