Abstract: An intrusion alarm system with an automatic exit control and a misset indicator which informs that someone has trespassed by opening a door during the resident's absence. This system comprises a sequential circuit which is enabled by mode selection by the resident at his/her going out and which stores the door's opening and closing signal produced as an output signal of a door open/closed detection circuit upon a second door opening, a misset alarm device which generates an alarm if the opening of the door is not detected within a predetermined time after the "Absent" mode is placed, and a timer circuit which is operated by the output signal of the sequential circuit and at the time-up to generate alarms. The sequential circuit can be cleared or disabled when the resident comes home and generation of an alarm is then prevented.