A fuel consumption evaluation system capable of quantitatively determining whether an operation saving a fuel is performed or an operation wastefully consuming the fuel is performed in an averaged way of operation, instructing, in consideration of also a change in the overall weight of a vehicle, a specific fuel-saved operation to a driver and/or an operation administrator based on the data thus determined, and attracting attention and instructing the driver on the fuel-saved operation in real time. The evaluation system comprises a control means evaluating a fuel consumption by using a measured engine rotational speed, an accelerator opening, a vehicle speed, and a fuel flow rate. The control means further comprises a storage means and is characterized in that an area from the start of running to the stop is grouped into multiple areas, a parameter on fuel consumption are set for each of the multiple areas, and based on a correlation between the parameters and the fuel consumption, a fuel consumption for each of the multiple areas is determined, and the evaluation is made based on the determined fuel consumption.