1. A driving assistance apparatus used in a vehicle, comprising: a report section that performs a report to a driver of the vehicle; an arrangement acquisition section that acquires an obstacle arrangement around a parking region serving as a target in a parking-region driving operation, the parking-region driving operation being at least either a driving operation to cause the vehicle to enter into the parking region or a driving operation to cause the vehicle to exit from the parking region; an arrangement memory that stores a past obstacle arrangement around the parking region in a first parking-region driving operation at a past time, the first parking-region driving operation at the past time being a parking-region driving operation different from and previous to a second parking-region driving operation at a present time, the past obstacle arrangement having been acquired by the arrangement acquisition section in the first parking-region driving operation at the past time; and an obstacle specification section that specifies a non-stationary obstacle that is an obstacle not stationary around the parking region, based on a difference between (i) the past obstacle arrangement stored in the arrangement memory in the first parking-region driving operation at the past time, and (ii) a present obstacle arrangement acquired by the arrangement acquisition section at the second parking-region driving operation at the present time, wherein the report section performs a report indicating presence of the non-stationary obstacle specified by the obstacle specification section.