We developed a method for simultaneous analysis of nine trichothecenes (nivalenol, deoxynivalenol, fusarenon-X, neosolaniol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, diacetoxyscirpenol, HT-2 toxin, and T-2 toxin). Trichothecenes in samples were extracted with acetonitrile-water (1 : 1) and purified using a QuEChERS kit and a multi-functional cartridge. Then they were quantified by LC-MS/MS using internal standards. LC with a pentafluorophenyl column and a mobile phase containing methanol enabled complete separation and highly sensitive quantification of the nine trichothecenes. Method validation with powdered corn soup samples demonstrated high linearity (>0.99) and accuracy ranging from 95% to 111% with good repeatability of 0.9% to 6.6% and reproducibility of 0.6% to 11.6%. The limits of detection and quantification were 0.01 to 0.75 μg/kg and 0.04 to 2.50 μg/kg, respectively. When 15 samples from powdered corn soups on the market were analyzed with this method, deoxynivalenol was detected in two samples (20.7 and 22.5 μg/kg, respectively), and 3-acetyldeoxynivalenol was concomitantly detected in one of them (13.5 μg/kg).