During a series of processes performed on a substrate in a substrate processing apparatus, processing history data containing items such as transport time, processing time, plate temperature, revolution per minute of spin motors and flow rate of solutions is obtained for each substrate. When a substrate with a process defect is detected in an inspection block, the processing history data on that substrate is compared with reference data. A processing unit or transport robot in which processing history data falls outside a predetermined range set as the reference data is judged as abnormal, whereby a defective processing unit or defective transport robot is identified. Thus provided is a substrate processing apparatus capable of identifying a defective processing unit or defective transport robot quickly and accurately.