Moving-body monitoring device

A monitoring device for a moving body that reciprocates in a first direction and a second direction opposite to the first direction, the monitoring device comprising:

• a position detection unit that detects a position of the moving body and outputs the position as positional information;
• a proximity sensor that detects passage of the moving body at a specific position;
• a first storage unit that stores a position of the moving body when the moving body moving in the first direction is detected by the proximity sensor, as first positional information, and stores a position of the moving body when the moving body moving in the second direction is detected by the proximity sensor, as second positional information;
• a calculation unit that calculates a fixed-point position in a detection area of the proximity sensor during monitoring, as fixed-point positional information, based on at least one of the first positional information and at least one of the second positional information stored in the first storage unit;
• a second storage unit that stores reference fixed-point positional information;
• and
• a monitoring unit that determines that an amount of positional deviation of the moving body exceeds tolerance when a deviation between the fixed-point positional information calculated by the calculation unit when monitoring the moving body and the reference fixed-point positional information stored in the second storage unit falls out of a prescribed range.