The research purposed to increase the efficiency of the warehouse management of Thamaruk Autopart Company Limited by adapting ABC Analysis to rectify the quality and time. The 3 instruments used for data collections are inventory record, products’ cost and quality record and flow process chart in order to record the procedure of pick-up in accordance with ABC principle and the planning used why-why analysis to analyze the problems and find the solutions. The study would compare the efficiency of warehouse management by using the statistics including percentage and mean to find the cost per product. According to the comparison in terms of accuracy, the efficiency is better or 62%, comparing to the pre-improvement at 38%. Regarding the efficiency in cost, it is also increased as the cost per product comparing to the pre-improvement, the cost per product was THB 403.46 while it reduced to THB 3.22, a decrease of THB 400.24. In terms of time efficiency, comparing to the pre-improvement, the operation required 34 minutes but after that the operation requires 21 minute, a reduction of 13 minutes or 61.76%.