The present invention relates to a measuring device using an electrical conductivity and having a function of informing electrode contamination. The measuring device includes a main body on which a display part is disposed on a surface thereof, and a control module controlling an operation of the measuring device is mounted therein, and a sensor unit disposed on one side of the main body and dipped into the object to measure electrical characteristics of the object to be measured. The sensor unit is driven by the control of the control module, and at least includes a first sensor electrode and a second sensor electrode for measuring electrical characteristics of the object to be measured. The sensor unit further includes a reference electrode disposed between the first and second electrodes at the same distance from each other.