A PID controller includes: a manipulated variable calculating portion that calculates a manipulated variable MV based on a set point SP and a process variable PV through a PID control calculation; a manipulated variable outputting portion that outputs a manipulated variable MV to outside of the controller; an alarm notifying portion that generates an alarm when a problem has been detected; a data recording portion that temporarily records time series data for the process variable PV; and a data storing portion that reads out and storing data recorded by the data recording portion 15 before and after the alarm event.