A machine tool includes three mutually independent data transmission mechanisms. The data transmission mechanisms include respective transmission units which assign codes for detecting errors to data acquired from the output of sensors, and which transmit the data. A machine controller includes an operation judgment unit which judges whether operation of a feed axis motor is continued. The operation judgment unit judges that operation is continued when there are two pieces of data for which a relationship between the data and the code matches a rule, and the two pieces of data are within a predetermined judgment range. The operation judgment unit judges that the feed axis motor is stopped when at least one of the pieces of data for which the relationship matches the rule deviates from the judgment range.