In a parallel database system having an execution device on a front end side and a plurality of execution devices on a database operation side (hereinafter referred to as the "divided data side"), the front end side analyzes a definition statement of a routine such as a function or a procedure inputted from a user to create routine execution process instructions for executing the routine. Simultaneously, the front end side determines whether or not a database operation statement is contained in the routine, and creates check information indicative of the determination result. The front end side analyzes a query statement inputted from the user to create a first query execution process instruction to be executed on the front end side and a second query execution process instruction to be executed on the divided data side. When the divided data side executes the query in accordance with the second query execution process instruction, a routine containing no database operation statement in the second query statement process instruction is executed on the divided data side.