To provide an interruption input unit and a PLC system capable of performing interruption in both cases of rise and fall of interruption input and extending width of application which can be interrupted.

An interruption pulse generating circuit 51 generates an interruption pulse 12a based on the contents of a trigger switching register 52 by receiving input of the interruption input 10 and generates the interruption pulse by using the rise of a signal as a trigger in the case of rise setting and by using the fall of the signal as the trigger in the case of fall setting.