In a system installed in a vehicle, a pickup unit repeatedly picks up a frame image of a target region including a road ahead of the vehicle, and an extracting unit extracts an edge of a lane marker formed on the road from each of the frame images. A creating unit creates a history of the edges of the lane marker for the respective frame images. A detecting unit detects pitch of the vehicle. The creating unit omits, as a target edge, an edge from the history of the edges for the respective frame images. The target edge to be omitted is extracted from a frame image that is picked up by the pickup unit with the pitch being detected by the detecting unit. A recognizing unit recognizes a region of the lane marker based on the history of the edges of the lane marker.