Provided are a method for preparing a granular animal feed additive and the granular animal feed additive prepared by the method. The method includes: filtering, with a membrane filter, a fermentation broth obtained from a lysine producing microorganism cultured in a lysine producing condition to obtain a lysine-containing filtrate and a microorganism-containing sludge; drying the filtrate to obtain a concentrate with a total solid content of 48 to 52 wt %; granule-drying the concentrate at a temperature of 50.degree. C. to 60.degree. C. to obtain granules; and coating the granules with a coating agent containing one or more selected from the group consisting of the sludge, a diluent or a free lysine as a lysine content adjustor, and a moisture prevention agent, to obtain lysine granules having the following properties: TABLE-US-00001 Lysine content (lysine sulfate) 65% or more Grain size 300 1,200 .mu.m, 90% or more Apparent density 620 720 kg/m.sup.3 Protein content 10 15% Total sugar content >0 1% Inorganic material content >0 3% Water content >0 3% Carboxylic acid content >0 8% SO.sub.4.sup.- ion content 20 25%.