A system for determining a road surface condition comprising: a plurality of vehicles (W i), each vehicle (W i) including on-board sensors (11, 12) for acquiring vehicular information, which is information on the behavior of a vehicle (W i) during travel, a feature value calculating means for calculating a plurality of feature values (X ij) for estimating the condition of the road surface on which the vehicle (W i) is traveling from the vehicular information acquired by the on-board sensors (11, 12), and a transmitting means for transmitting the feature values (X ij) to the outside of the vehicle (W i); a server for accumulating the feature values (X ij) transmitted from the transmitting means of each of the plurality of vehicles (W i); and a road surface condition determining unit for determining a road surface condition using the accumulated feature values (X ij) of the plurality of vehicles (W i), the road surface condition determining unit being characterized by comprising: a feature value calculated value calculating means for calculating feature value calculated values (X j), which are the calculated values (X j) based on feature values (X ij) from the plurality of vehicles (W i) at a location within a predetermined range within a predetermined space of time, for the plurality of feature values (X ij), respectively; a feature value identification value calculating means for calculating feature value identification values (Y R) to be obtained by inputting the plurality of feature value calculated values (X j) to the respective road surface identification functions (Y R) set in advance for the respective road surface conditions, for the respective road surface identification functions (Y R); and a road surface condition determining means for determining the road surface condition at the location within the predetermined range within the predetermined space of time, using the feature value identification values (Y R) calculated for the respective road surface identification functions (Y R). a plurality of vehicles (W i), each vehicle (W i) including on-board sensors (11, 12) for acquiring vehicular information, which is information on the behavior of a vehicle (W i) during travel, a feature value calculating means for calculating a plurality of feature values (X ij) for estimating the condition of the road surface on which the vehicle (W i) is traveling from the vehicular information acquired by the on-board sensors (11, 12), and a transmitting means for transmitting the feature values (X ij) to the outside of the vehicle (W i); on-board sensors (11, 12) for acquiring vehicular information, which is information on the behavior of a vehicle (W i) during travel, a feature value calculating means for calculating a plurality of feature values (X ij) for estimating the condition of the road surface on which the vehicle (W i) is traveling from the vehicular information acquired by the on-board sensors (11, 12), and a transmitting means for transmitting the feature values (X ij) to the outside of the vehicle (W i); a server for accumulating the feature values (X ij) transmitted from the transmitting means of each of the plurality of vehicles (W i); and a road surface condition determining unit for determining a road surface condition using the accumulated feature values (X ij) of the plurality of vehicles (W i), the road surface condition determining unit being characterized by comprising: a feature value calculated value calculating means for calculating feature value calculated values (X j), which are the calculated values (X j) based on feature values (X ij) from the plurality of vehicles (W i) at a location within a predetermined range within a predetermined space of time, for the plurality of feature values (X ij), respectively; a feature value identification value calculating means for calculating feature value identification values (Y R) to be obtained by inputting the plurality of feature value calculated values (X j) to the respective road surface identification functions (Y R) set in advance for the respective road surface conditions, for the respective road surface identification functions (Y R); and a road surface condition determining means for determining the road surface condition at the location within the predetermined range within the predetermined space of time, using the feature value identification values (Y R) calculated for the respective road surface identification functions (Y R). a feature value calculated value calculating means for calculating feature value calculated values (X j), which are the calculated values (X j) based on feature values (X ij) from the plurality of vehicles (W i) at a location within a predetermined range within a predetermined space of time, for the plurality of feature values (X ij), respectively; a feature value identification value calculating means for calculating feature value identification values (Y R) to be obtained by inputting the plurality of feature value calculated values (X j) to the respective road surface identification functions (Y R) set in advance for the respective road surface conditions, for the respective road surface identification functions (Y R); and a road surface condition determining means for determining the road surface condition at the location within the predetermined range within the predetermined space of time, using the feature value identification values (Y R) calculated for the respective road surface identification functions (Y R).