Abstract: Connector housings having plural kinds of terminals (plated with different materials, e.g.) are mounted at predetermined locations, positioned and secured by a drive means. A sensor probe which receives a light, of a color detection device, is transferred successively to the locations opposite to the terminals. A color sensor senses a level of a specific color component of the light received by the sensor probe. The sensed level is compared with a predetermined reference level and it can be determined based upon whether the sensed level is higher than the reference level, the kind of the terminals in the connector housings.