A measurement device 10 includes a measurement cell 11. The measurement cell 11 includes a substrates 17 and a substrate 16 formed on the substrate 17. The substrates 16 and 17 are bonded to each other. Thus, a flow pass 9 is formed in the measurement cell 11. As shown in FIG. 3, on the substrate 17 of the measurement cell 11, provided are a concave well 19, a protruding microelectrode 1 connected to a terminal 4a and formed on a side wall surface of the well 19, communicating tubes 15a and 15b connected to both of side surfaces of the well 19 (i.e., the flow pass 9) to face to each other, resistance baths 6a and 6b connected to the communicating tubes 15a and 15b, thin film resistors 3a and 3b arranged in the resistance baths 6a and 6b, and a reference electrode 2 connected to a terminal 4b.