The research titled “Applications Granules Fertilizer Sea Fish Waste As a source of organic-N on Mustard Cultivation (Brassica juncea (L.) of Tosakan Variety” was carried out in the Green House, Faculty of Agriculture, Universitas Muhammadiyah Yogyakarta from July up to August 2016. This research was conducted using environmental method and arranged in Completely Randomized Design (CRD) with single factor. The treatments were consisting of 0.65 grams of Urea / plant (P1), 14.7 grams of granules fertilizer Sea Fish Waste / plant (P2), 0.16 grams of urea / plant + 1.58 grams of granules fertilizer Sea Fish Waste / plant (P3), 0.32 grams of urea / plant + 1.05 grams of granules fertilizer Sea Fish Waste / plant (P4), and 0.48 grams of Urea / plant + 0.52 grams of granules fertilizer Sea Fish Waste / plant (P5). The results showed that granules fertilizer of Sea Fish Waste can serve as source of organic-N in the process of growth and yield of mustard Tosakan variety. Treatment (P2) 14.7 gram/plant equal to 2.94 tons/hectare gave the potential yield 79.004 tons/ hectare