An information processing device includes a memory and a processor coupled to the memory. The processor acquires a first image at a first time and a second image at a second time later than the first time from a monocular camera mounted on a vehicle, calculates an amount of movement of the vehicle based on a sensor value acquired during a measurement period between the first time and the second time, outputs a result of distance measurement using a first distance measurement method to perform distance measurement using the first image or the second image or a second distance measurement method to perform distance measurement using the first image and the second image, depending on the amount of movement and outputs a result of calculation of a route to guide the vehicle to a parking space, based on the result of distance measurement.