An annealing apparatus includes a heater plate and a cooler plate disposed in a chamber, a delivering robot, a sensor and circuitry. The delivering robot is configured to deliver a wafer between the heater plate and the cooler plate in the chamber. The sensor is located on the delivering robot and configured to output a first signal in response to a motion of the delivering robot. The circuitry is coupled to the sensor and configured to detect whether an abnormality of the delivering robot occurs according to the first signal.