This paper is to examine the degree of the farm income instability due to the outsider factors. The degree of the farm income instability is measured and analysed as its' mean and variance during 1998～2002. In order to categorize the degree of instability in the farm economy, the farm households are classified according to the some characteristic variables such as farmer's age, standardized farming size, the level of household receipt, and the size of household debt and its ratio to the asset. This paper analysis the farm income fluctuation with the panel data of the 1998~2002 Farm Household Economy Survey in Korea. The results implies the importance of policies for income stabilization.