In this paper, we propose a novel approach to estimate three types of phone mismatch penalty matrices for two-state keyword spotting. When the output of a phone recognizer is given, text matching with the phone sequences provided by the specified keyword using the proposed phone mismatch penalty matrices is carried out to detect a specific keyword. The penalty matrices which is estimated from the training data through deliberate error generation are accounting for substitution, insertion and deletion errors. In comparative experiments on a Korean continuous speech recognition task, the proposed approach has shown a significant improvement.