A technique capable of detecting harmful behavior such as power harassment, sexual harassment, or bullying in work environment to support handling is provided. A harmful behavior detecting system includes a computer that executes observation and detection regarding harmful behavior including power harassment, sexual harassment, and bullying among people in work environment. The computer obtains voice data into which voice around a target person is inputted; obtains voice information containing words and emotion information from the voice data; and obtains data such as vital data, date and time, or a location of the target person. The computer uses five elements including words and an emotion of the other person, words, an emotion, and vital data of the target person to calculate an index value regarding the harmful behavior; estimate a state of the harmful behavior based on the index value; and output handling data for handling the harmful behavior in accordance with the estimated state.