This present invention provides a portable navigation apparatus with a refueling prompt function, characterized in that the memory comprises a driving style table and a fuel consumption reference database, and the processing unit comprises a fuel recording unit and a refueling prompt unit. Wherein, while a vehicle approaches a gas station near the navigation route, or while a new route or a re-planned route is generated, the refueling prompt unit is able to automatically calculate forecasting fuel consumption required for traveling from a current location to a next gas station near a navigation route according to the navigation route generated by the route navigation unit, the driving style table and the fuel consumption reference database, and prompting an alarm signal when the forecasting fuel consumption is greater than the fuel quantity to remind a user to refuel firstly.