Present disclosure provides a travel assistance device which comprises: a road detection unit that obtains an infrared image in front of a vehicle from an infrared imaging unit that is mounted on the vehicle, and detects a road end line of a road on which the vehicle travels from the captured infrared image; a division line detection unit that obtains a visible image in a range corresponding to a range indicated by the infrared image from a visible imaging unit that is mounted on the vehicle, and detects a division line of the road from the captured visible image; an image generation unit that generates an integrated image indicating the road end line and the division line on the basis of the infrared image and the visible image registered with each other; and a division line estimation unit.