An information processing system, comprising: a history obtainer that obtains a personal driving environment history of each of a plurality of drivers, each of the personal driving environment histories indicating one or more behaviors, of a vehicle, selected by the driver, and a driving environment associated with each of the one or more behaviors, the driving environment being a driving environment of the vehicle at a point in time of selection of the behavior it is associated with; a modeler that models, from a driving environment history including the personal driving environment histories of the plurality of drivers, the personal driving environment history of at least one of the plurality of drivers, to build a driver model indicating a relationship between a behavior and a driving environment for the vehicle of the at least one of the plurality of drivers; an environment obtainer that obtains a driving environment of a vehicle of a driver that is a target for estimation; a behavior estimation unit configured to, in the driver model built, estimate a behavior associated with the driving environment obtained by the environment obtainer, as a behavior of the vehicle of the driver that is the target for estimation; and a display unit (101, 105) configured to display a behavior candidate wherein each of the personal driving environment histories of the plurality of drivers indicates, for each behavior, of the vehicle, selected by the driver, a first parameter set which is a parameter set including each value of at least one environment parameter, as the driving environment of the vehicle at the point in time of selection of the behavior, and a second parameter set which is a parameter set including each value of at least one environment parameter, as the driving environment at the time a corresponding behavior was displayed as the behavior candidate, models the value of each environment parameter included in the first parameter set and the value of each environment parameter included in the second parameter set indicated in the personal driving environment history of the at least one of the plurality of drivers, to build the driver model indicating a relationship between a behavior, the first parameter set, and the second parameter set for the vehicle of the at least one of the plurality of drivers, the environment obtainer obtains the driving environment of the vehicle of the driver that is the target for estimation as a parameter set, and characterized in that the behavior estimation unit is configured to, in the driver model built, estimate a behavior associated with the first parameter set or the second parameter set that has a degree of similarity exceeding a predetermined threshold with the parameter set obtained by the environment obtainer, as a behavior of the vehicle of the driver that is the target for estimation. a history obtainer that obtains a personal driving environment history of each of a plurality of drivers, each of the personal driving environment histories indicating one or more behaviors, of a vehicle, selected by the driver, and a driving environment associated with each of the one or more behaviors, the driving environment being a driving environment of the vehicle at a point in time of selection of the behavior it is associated with; a modeler that models, from a driving environment history including the personal driving environment histories of the plurality of drivers, the personal driving environment history of at least one of the plurality of drivers, to build a driver model indicating a relationship between a behavior and a driving environment for the vehicle of the at least one of the plurality of drivers; an environment obtainer that obtains a driving environment of a vehicle of a driver that is a target for estimation; a behavior estimation unit configured to, in the driver model built, estimate a behavior associated with the driving environment obtained by the environment obtainer, as a behavior of the vehicle of the driver that is the target for estimation; and a display unit (101, 105) configured to display a behavior candidate wherein each of the personal driving environment histories of the plurality of drivers indicates, for each behavior, of the vehicle, selected by the driver, a first parameter set which is a parameter set including each value of at least one environment parameter, as the driving environment of the vehicle at the point in time of selection of the behavior, and a second parameter set which is a parameter set including each value of at least one environment parameter, as the driving environment at the time a corresponding behavior was displayed as the behavior candidate, models the value of each environment parameter included in the first parameter set and the value of each environment parameter included in the second parameter set indicated in the personal driving environment history of the at least one of the plurality of drivers, to build the driver model indicating a relationship between a behavior, the first parameter set, and the second parameter set for the vehicle of the at least one of the plurality of drivers, the environment obtainer obtains the driving environment of the vehicle of the driver that is the target for estimation as a parameter set, and characterized in that the behavior estimation unit is configured to, in the driver model built, estimate a behavior associated with the first parameter set or the second parameter set that has a degree of similarity exceeding a predetermined threshold with the parameter set obtained by the environment obtainer, as a behavior of the vehicle of the driver that is the target for estimation.