To exactly decide that a syringe pump device is in abnormal conditions or approaches the abnormal conditions by simply diagnosing the conditions of the syringe pump device, and to take measures for the abnormal conditions in advance.

This method diagnoses the abnormal conditions of the syringe pump device 1 which has a syringe 4 composed of a cylinder 2 and a piston 3, and sucks or discharges fluid to/from the cylinder 2 by reciprocating the piton 3. There is arranged a stress sensor for obtaining a detection value corresponding to stress which is generated in the cylinder 2 by the reciprocation of the pitons 3, the detection value detected by the stress sensor is compared with a reference value which is obtained in advance, and it is determined that the syringe pump device is in the abnormal conditions when the detection value approaches or reaches the reference value.