An obstacle detecting and notifying device according to an embodiment is to be installed in a vehicle, to issue an alarm upon detecting a moving obstacle. The device includes a moving-obstacle detector that detects a moving obstacle in a given monitoring area; a first calculator that calculates an expected moving route of the moving obstacle; a second calculator that calculates an expected moving route of the vehicle; a setter that sets an alarm area in the monitoring area in accordance with the expected moving route of the vehicle, the alarm area in which the alarm is to be issued; an excluder that excludes, from alarming moving obstacles, the moving obstacle unlikely to reach the alarm area, in accordance with the expected moving route of the moving obstacle and the expected moving route of the vehicle; and an alarm that issues an alarm against the alarming moving obstacles.