NOVELTY - Fuel oil is manufactured by performing duration circulation of enzyme-containing water in 1st circulation route (R1) formed by water tank (1) containing an enzyme, deaeration part (10, 13), mineral part, and mixer (11, 14) after placing enzyme into water, mixing, and aerating, performing circulation duration of raw material oil and mixed oil with surfactant in 2nd circulation route (R2) formed by mixing oil-and-water tank (5), deaeration part, mixer, and temperature control part, and performing duration circulation of mixing oil and water with circulated mixed oil 2nd circulation route.    USE - Manufacture of fuel oil (claimed).    ADVANTAGE - Dispersion and mixing of water in raw material oil is easy, oil and water do not separate over a long period of time, transparent commercially valuable fuel oil can be generated, stable fuel oil can be taken out efficiently, air component and mineral in water are effectively removable, and fuel efficiency is improved.    DETAILED DESCRIPTION - Fuel oil is manufactured by performing duration circulation of enzyme-containing water in 1st circulation route (R1) formed by water tank (1) containing an enzyme, deaeration part (10, 13), mineral part, and mixer (11, 14) after placing enzyme into water, mixing, and aerating, performing circulation duration of raw material oil and mixed oil with surfactant in 2nd circulation route (R2) formed by mixing oil-and-water tank (5), deaeration part, mixer, and temperature control part, performing duration circulation of mixing oil and water with circulated mixed oil 2nd circulation route, separating into transparent-layer part (M) which is at the upper side inside of the tank and milky-white layer part (N) containing oil component which settles at the bottom by performing duration stationary of mixing oil and water circulated at 2nd circulation route within oil-and-water stationary tank (8), and taking out transparent-layer part as fuel oil.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of a fuel oil manufacturing system.    Water tank (1)    Mixing oil-and-water tank (5)    Oil-and-water stationary tank (8)    Deaeration part (10, 13)    Mixer (11, 14)    Transparent-layer part (M)    Milky-white layer part (N)    1st circulation route (R1)    2nd circulation route (R2)