A method for the determination of ipfencarbazone in agricultural products, livestock products and seafood by LC-MS/MS was developed. Agricultural samples were extracted with acetone. An aliquot of crude extract was partitioned with n-hexane and sat. sodium chloride solution. Clean-up was performed using GC/PSA and C18 cartridges. In the case of livestock products and seafood, samples were extracted with a mixture of acetone and n-hexane, and the organic layer was collected. After acetonitrile-hexane partitioning, the extract was cleaned up using PAS and C18 cartridges. The gradient LC separation was performed on a C18 column with acetonitrile-water containing acetic acid as a mobile phase, and MS with positive ion electrospray ionization was used for detection. The average recoveries (n=5) of ipfencarbazone from 16 kinds of agricultural products, livestock products and seafood spiked at the MRLs or at the uniform limits (0.01 ppm) were 73-101%, and the relative standard deviations were 1.3-5.1%. The limit of quantitation of the developed method was 0.01 mg/kg for ipfencarbazone.