With the expansion of the areas of database applications, the amount of data processed has become gigantic, and the demand for faster database systems has increasingly intensified. Thus, many efforts have been expended to execute database operations more efficiently using special hardware. However, for the cases in which mass-produced LSI cannot be used, cost has become excessive, and replacement methods have been sought. Vector processors have powerful pipeline operators and large-capacity main memories and have rapidly spread in recent years. In this paper, algorithms for relational database operations suitable for vector processors showing the characteristics of vector processors sufficiently are presented. This algorithm is based on the hash method, which is highly efficient when the capacity of the main memory is large, and it is shown that a rate of acceleration more than 10 times the average is obtained for representative relational database operations when this algorithm is executed on a vector processor. © 2000 Scripta Technica, Syst Comp Jpn, 31(8): 7988, 2000