To provide a presence-in-residence situation notification system which, without any operation performed by a user, automatically notifies a specific user of the situation of the presence/absence in a residence.

The presence-in-residence situation notification system comprises: a router having a router function and a wireless LAN access point function; and a notification destination terminal connected to the router through a network. The router comprises control means which, when a slave set terminal is assigned to the router or when the assignment of the slave set terminal to the router is cancelled, generates a presence-in-residence situation notification mail and transmits the mail to the notification destination terminal.