A driving-environment setup system has a plurality of portable devices, each of which transmits a feature identification information item used for identifying a physical feature of an associated user of the each of the plurality of portable devices and transmits an environment identification information item used for identifying a driving environment for the associated user. An in-vehicle device of the system detects a physical feature of a person sitting in a driver's seat and identifies one of the associated users as a driver when the physical feature identified based on the received feature identification information item of the one of the associated users corresponds to the detected physical feature. The in-vehicle device sets a driving environment for the driver based on the received environment identification information item.