A biosensor and a method for recognizing a liquid sample are provided, which can recognize whether a sample is introduced by recognizing an inside of a sample introduction channel through measurement of capacitance. The biosensor includes an upper plate and a lower plate facing each other, a middle plate interposed between the upper plate and the lower plate to form a sample introduction channel through a recess portion, a working electrode and an auxiliary electrode formed in the sample introduction channel, a sample recognition electrode formed on an outside of the sample introduction channel in a position that corresponds to the sample introduction channel, and a capacitance measurement portion electrically connected to any one of the working electrode and the auxiliary electrode and the sample recognition electrode.
