To provide a database managing device whereby the number of processes in an idle state is reduced and a parallel degree is adjusted based on the execution result of the low-order process.

The device processes a retrieval request as against data stored in plural secondary storage devices in parallel through the user of the plural server processes which execute an operation in plural processors. In this case, a retrieval request dividing means 102 which analyzes the retrieval request and divides it into the operations of a parallel execution unit as against the plural server processes and a paralle execution control means 103 which decides the optimum parallel degree based on the state of system resources with the parallel execution unit operation as an input, starts the plural server processes so as to execute the operation and returns a retrieval result by summarizing the respective results are provided and the parallel execution control means 103 starts the server process in bottom-up when the retrieval request to be executed in parallel is nested.