. Ameriana, M. 2008. Farmer's's Behavior in Using Chemical Peststicide on Vegetablble. The use of chemical pesticides at the vegetable farmer's level has been indicated to be excessive, and it was hazardous to environment and human health. This study was aimed to assess the tomato farmer's behavior in using chemical pesticides and factors that may influence this behavior. A survey was carried out on June-July 2004 on tomato production centers, Lembang and Pangalengan, Bandung District. There were 156 respondents (farmers) interviewed in this study. Research location (subdistrict and village) were selected purposively based on the largest tomato planted area. Respondents were selected by using stratified random sampling, based on their farm size. Data were analyzed by using descriptive statistics and path analysis. The results showed that tomato farmer's behavior was influenced by (1) farmer's perception on risks, the higher the risk perception the higher the quantity of chemical pesticide used, (2) farmer's perception on cultivar resistance to tomato pests, the lower the cultivar resistance the higher the quantity of chemical pesticide used, (3) farmer's knowledge on the danger of pesticides, the lower the knowledge, the higher the quantity of chemical pesticide used.