About 40.78 percent of paddy soils in Jombang, East Java Province is contaminated by endosulfan.. Endosulfan insecticide is persistent, bio-accumulative, and extremely toxic for biota particularly fish. This study aims to provide solutions for improving endosulfan contaminated soils using corn cob waste. Agricultural waste of corn cob in the form of biochar has the potency to be utilized as remedial for endosulfan which contaminated soils and as the fertilizer of paddys soils. The research results showed that (1) the field study potentially holds corn cob waste of 13,270 tons per year which is equivalent to 3551.25 tons of biochar, (2) the corn cob biochar has the best characteristic compared to other biochars of agricultural waste, and (3) the application of biochar 400 kg ha-1 combined compost (1:4) can remediate 8.88 ha (126%) of heavy contamination area or remediate 56% of contaminating (>MRLs) and (<MRLs) areas. This research highlights the potency of corn cob waste to be used by farmers in Jombang District to recovery almost half of the total endosulfan contaminated paddy soil in the area which can be applied in the other area with a similar ecological characteristic. The corn cob biochar technology usage combined to compost could reduce endosulfan residue and also increase paddy soils fertility, and finally increase rice grain yield.