An information processing apparatus comprising: an acquirer configured to acquire observation information and position information in time series, wherein the observation information is a captured image obtained through imaging by an imaging unit that images the area surrounding a vehicle, and wherein the position information is a position and posture of the vehicle; an attribute determiner configured to, every time the acquirer acquires the observation information and position information: determine, based on the observation information, an attribute of each of a plurality of areas into which the area surrounding the vehicle is divided, wherein determining the attribute of each of the plurality of areas comprises determining an attribute of a plurality of pixels included in the captured image, projecting the attributes on a road surface on the basis of positional relationship information between the imaging unit and the road surface, and transforming into pixels of an upper surface image as viewed from above the road surface, wherein the attribute is determined as a roadway or as other than the roadway, and a setter configured to set reliability of the attribute for each of the areas, wherein the setter sets reliability of the attribute of a given area from the attribute of the given area and one or more attributes of one or more corresponding areas determined in the past, each of the corresponding areas being at a same position as the given area, wherein the setter sets the reliability to be a higher value as the number of the corresponding areas indicating a same attribute as the given area is larger, and sets the reliability to be a lower value as the number of the corresponding areas indicating the same attribute as the given area is smaller, wherein the setter identifies the one or more corresponding areas on the basis of the position information, wherein an amount of movement of the vehicle between the time and a previous time is calculated from the position information, and areas at the previous time corresponding to the areas at the time are obtained on the basis of the amount of movement of the vehicle. an acquirer configured to acquire observation information and position information in time series, wherein the observation information is a captured image obtained through imaging by an imaging unit that images the area surrounding a vehicle, and wherein the position information is a position and posture of the vehicle; an attribute determiner configured to, every time the acquirer acquires the observation information and position information: determine, based on the observation information, an attribute of each of a plurality of areas into which the area surrounding the vehicle is divided, wherein determining the attribute of each of the plurality of areas comprises determining an attribute of a plurality of pixels included in the captured image, projecting the attributes on a road surface on the basis of positional relationship information between the imaging unit and the road surface, and transforming into pixels of an upper surface image as viewed from above the road surface, wherein the attribute is determined as a roadway or as other than the roadway, and a setter configured to set reliability of the attribute for each of the areas, wherein the setter sets reliability of the attribute of a given area from the attribute of the given area and one or more attributes of one or more corresponding areas determined in the past, each of the corresponding areas being at a same position as the given area, wherein the setter sets the reliability to be a higher value as the number of the corresponding areas indicating a same attribute as the given area is larger, and sets the reliability to be a lower value as the number of the corresponding areas indicating the same attribute as the given area is smaller, wherein the setter identifies the one or more corresponding areas on the basis of the position information, wherein an amount of movement of the vehicle between the time and a previous time is calculated from the position information, and areas at the previous time corresponding to the areas at the time are obtained on the basis of the amount of movement of the vehicle.