The type of work in West Sumatra is thought to be influenced by factors in the area of ​​residence, sex, field of study, highest education completed, and work experience. To see the factors that influence the type of work used the classification tree method in CART (Classification & Regression Tree). The classification tree method is used to estimate the effect of explanatory variables on categorical response variables starting from the initial tree formation by sealing, determining the best sealing, stopping the sealing, trimming, to selecting the best tree and determining the estimated response value. The data used in this study are 6068 residents of West Sumatra who have worked with the highest education of at least a high school equivalent of the raw data from the National Labor Force Survey (National Labor Force Survey) in August 2007. Based on the results of CART analysis using the classification tree method, a tree is obtained the optimum classification consists of 1 root node, 3 deep nodes, and 5 final nodes. The first node is divided by the variable field of study, then the node included in the variable is the area of ​​residence, the field of study, and gender. The final 5 knots state the 5 groups of people who have main jobs, where 2 groups are dominated by the type of work of professional staff, technicians and other workers. Therefore it can be concluded that the factors that influence the type of occupation of the population of West Sumatra are the field of study, area of ​​residence and gender.