This paper deals with personal information recognition in machine tool operation. First, a measuring system concerning a lathe was constructed. The system samples pulse, respiration, and galvanic skin response as biological information and revolution of handles and grip pressure changes as operative information. Next, the relationships between the processed indexes and personal information were investigated. A personal information identifying system, capable of recognizing, "concentration", "mental strain" and "less consciousness" in real-time as well as skill of the operator during machine tool operation was developed. The results of the experiments confirm the possibility of identifying the personal information.