PURPOSE: To enable to uniformly apply a very small amount of grease to desired thickness, by pressurizing grease in a state diluted to point viscosity with a volatile diluent under high pressure, and airless spraying said grease through a nozzle.

CONSTITUTION: Diluted grease 40 prepd. by diluting grease to high viscosity with a volatile diluent 37 is pressurized under high pressure by the action of a pressure pump 14 and airless sprayed through a spray nozzle 8, to apply said grease onto a work 10 being received in the work receiver 9b of a spray box 9. Its application amount onto the work 10 is controlled by the pressure and concentration of the diluted grease 40 and its applying time. Hence, the very small amount of the grease can be uniformly applied to desired thickness.