A sound state estimating unit detects surrounding sound at a timing at which a notification to a destination user occurs. A user state estimating unit detects a position of the destination user and positions of users other than the destination user at the timing at which the notification occurs. An output control unit controls output of the notification to the destination user at a timing at which it is determined that the surrounding sound detected by the sound state estimating unit is masking possible sound which can be used for masking in a case where the position of the destination user detected by the user state estimating unit is within a predetermined area.