Abstract: A server apparatus includes: a communication unit that communicates with a first communication apparatus and a second communication apparatus; a registration unit that, upon obtaining identification data of a mobile terminal which has been lost from the first communication apparatus, registers the identification data; and an output unit that, upon obtaining position data and the identification data from the second communication apparatus, outputs the position data when the identification data is registered, the position data indicating a position of the second communication apparatus at the time when the second communication apparatus receives the identification data sent from the mobile terminal.