An apparatus and a method for recognizing a horn using a sound signal processor are provided. The apparatus includes a data storage unit configured to acquire and store surrounding sound data and a sound signal processor configured to sample a sound signal within the sound data, perform signal conversion, and define and extract the frequency signals. In addition, a horn recognizer is configured to combine the extracted frequency signals, accumulate the frequency signals, and digitize a change rate of the accumulated frequency signals. Further, an output data determiner is configured to determine whether the digitized change rate of the frequency signals is equal to or greater than a threshold value to determine whether and when the horn is generated.