An information processing apparatus comprising: a position acquiring unit configured to acquire position information representing a position where a target exists or no target exists, the position being measured by a sensor; an occupancy level calculating unit configured to calculate an occupancy level distribution representing a level of occupancy, by the target, of each of a plurality of regions existing along a direction from the position of the sensor to the position indicated by the position information, based on the position information and measurement accuracy of the sensor, the occupancy level distribution being based on a non-measurement probability distribution representing a probability that measurement is not performed by the sensor (10B, 10C); an existence probability deriving unit configured to derive an existence probability distribution representing an existence probability of the target, the existence probability distribution changing depending on the measurement accuracy, based on the position information and the measurement accuracy; and a non-measurement probability deriving unit configured to derive the non-measurement probability distribution by integrating the existence probability in a direction from the position of the sensor to the position indicated by the position information, the existence probability distribution being defined as a normal distribution function, wherein the occupancy level calculating unit is configured to calculate the occupancy level distribution based on the existence probability distribution and the non-measurement probability distribution, and wherein the occupancy level calculating unit is configured to calculate the occupancy level distribution based on a weighted sum of the existence probability distribution and the non-measurement probability distribution. a position acquiring unit configured to acquire position information representing a position where a target exists or no target exists, the position being measured by a sensor; an occupancy level calculating unit configured to calculate an occupancy level distribution representing a level of occupancy, by the target, of each of a plurality of regions existing along a direction from the position of the sensor to the position indicated by the position information, based on the position information and measurement accuracy of the sensor, the occupancy level distribution being based on a non-measurement probability distribution representing a probability that measurement is not performed by the sensor (10B, 10C); an existence probability deriving unit configured to derive an existence probability distribution representing an existence probability of the target, the existence probability distribution changing depending on the measurement accuracy, based on the position information and the measurement accuracy; and a non-measurement probability deriving unit configured to derive the non-measurement probability distribution by integrating the existence probability in a direction from the position of the sensor to the position indicated by the position information, the existence probability distribution being defined as a normal distribution function, wherein the occupancy level calculating unit is configured to calculate the occupancy level distribution based on the existence probability distribution and the non-measurement probability distribution, and wherein the occupancy level calculating unit is configured to calculate the occupancy level distribution based on a weighted sum of the existence probability distribution and the non-measurement probability distribution.