Rice seed-borne pathogenic fungi are one of the causes of decreased rice productivity. Nanoemulsion of citronella oil is an alternative control for seed-borne pathogenic fungi carried by rice seeds and is effective and environmentally friendly. The research aimed to determine the effective concentration of nanoemulsions of citronella oil in controlling rice seed-borne pathogenic fungi. The study was conducted in two stages: 1. In the laboratory using a completely randomized design (CRD) with seven treatments and four replications. 2. Greenhouse uses the same design and treatment in stage one. The treatments used were control (soaking using sterile distilled water), nanoemulsion of citronella oil concentrations of 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, and synthetic fungicide with propineb active site (70 WP) at a 2 g/l. The data obtained were analyzed using variance with the advanced test of Least Significance Different (LSD) at the 5% level. The parameters observed were the percentage of rice seeds that were attacked by fungi, identification of seed-borne pathogenic fungi, percentage of rice seeds that were attacked by each fungus, percentage of seedlings that appeared in the field, percentage of seedlings attacked by fungi, percentage of dead seedlings, seedling height, fresh and dry weight of seedlings. The result showed that nanoemulsion with a concentration of 0.50% was the most effective in controlling rice seed-borne pathogenic fungi, with the effectiveness of seeds being attacked suppressed by fungus, seedlings appearing in the field, seedlings being attacked by fungus, dead seedlings, seedling height, fresh and dry weight seeds were 75.00%, 60.00%, 100.00%, 100.00%, 60.83%, 141.55%, 366,67% respectively.