A filler material for an organic electroluminescent element, formed of a resin composition being liquid at 25° C., and containing a organometallic compound and a hydrocarbon polymer having a number average molecular weight of 300 or more and less than 20,000, and an iodine value less than 40 g/100 g, and having no polar group, wherein a contact angle to silicon nitride is 10 to 40 degrees, and an amount of outgassing other than moisture upon being heated at 85° C. for 1 hour is 500 ppm or less in terms of a toluene equivalent, and a method of sealing an organic electroluminescent element using the same.