1. An apparatus for removing noise from biosignals measured for a particular period of time, the apparatus comprising: a selection unit configured to select a target signal from a plurality of the biosignals; a similarity calculating unit configured to calculate a similarity between the target signal and other biosignals, wherein the similarity calculating unit comprises, an alignment unit configured to aligning the biosignals with respect to an R peak of a QRS complex wave form included in the biosignals, a search window setting unit configured to set a range of a search window to include the target signal and biosignals within a particular range centering around the target signal, a unit window setting unit configured to set a size of a unit window within the search window, and a calculating unit configured to calculate a similarity between signals included in a first unit window centering around the target signal and signals included in a second unit window centering around the other biosignals in the search window, wherein the calculating unit calculates the similarity between the target signal and the other biosignals based on a sum of absolute deviation (SAD) between the first unit window and the second unit window for each of the other biosignals; and a noise removal unit configured to remove noise from the target biosignal by using the similarity, wherein the noise removal unit comprises, a weight calculating unit configured to calculate weights for the biosignals in the search window respectively by using the similarity, and a weighted averaging unit configured to calculate a weighted average of the biosignals in the search window by using the weights and to remove noise from the target signal based on the weighted average of the biosignals.