The present invention provides a comb electrode for a signal processing unit to electrically contact with a living body. The comb electrode comprises an electrode plate and a plurality of electrode columns. The plurality of electrode columns are protrudingly configured on the electrode plate, and comprise at least one main electrode column and at least one reference electrode column. Moreover, the plurality of electrode columns are electrically connected with a signal processing unit. As a result, the main electrode column can achieve the effect of reducing the drift error of electric signal level in transmission of electric signals by comparing with the reference level of the reference electrode column.
