This study was investigated to determine the residual amounts of acetamiprid in amaranthus (Amaranthus mangostanus L.) using high performance liquid chromatography with ultraviolet detector (HPLC/UVD) and to assess the standard for safe use of acetamiprid 5% SL. Acetamiprid is used to control the green peach aphid (Myzus persicae) on amaranthus. Recovery tests of acetamiprid in amaranthus were done by spiking 10 and 50-times of limit of detection (LOD). Recoveries obtained from two concentrations were 81.98% and 79.52%, respectively. The residual amount of acetamiprid from the amaranthus harvested 3, 7 and 10 days after 1 and 2-times treatment ranged from 0.06 to 1.63 mg/kg. Because the maxium residue limit (MRL) of acetamiprid in the amaranthus is 3.0 mg/kg (Provisional MRLs, Brassica leafy vegetables, KFDA), it is proposed for acetamiprid 5% SL to apply 2 times, 3 days before harvest in Korea.