PURPOSE: To diagnose existence of abnormality by detecting the precursory data of trouble generation in a ladle crane.

CONSTITUTION: A motor bearings of a ladle crane 1, a gear reducer 8, a drum 9, bearings 10, a temperature sensor 21 and/or a vibration sensor 22 for rotation of brake pulley and the like are placed and also a data logger 23 is placed on the ladle crane 1. By recording the data detected with the temperature sensor 21 and/or vibration sensor 22 in a data logger 23, diagnosis is done based on the recorded data. Thus, replacement and renewal basis for equipment can be clarified and the data can be used as basic data for equipment improvement.