Although techniques for determining the positions of workers and products and displaying their tracks on a two-dimensional layout were available in the past, they were inconvenient in that work times and process shifts over time could not be grasped. A technique for grasping work contents of a worker highly accurately utilizing electronic tags was also available. However, it was also inconvenient in that the workers had to read the electronic tags intentionally while at work. The work information processor (100) is capable of showing passage of time and process shifts by specifying steps at given points in time by a position sensor (161) attached to a worker. Also represented is a work information processor that stores work content definition information for specifying work contents based on the information detected by the sensor and displays work contents along the passage of time, specifies work contents based on values detected by multiple sensors and the times of said detections according to work content definition information, and specifies work contents according to pieces of work content definition information.