Provided is a method of changing the configuration of a shared-nothing database system without shutting down the system. The configuration changing method for a shared-nothing database system includes plural database servers, a storage which provides data areas to the database servers, and a management server which has a database management system and divides a transaction to allocate pieces of the transaction to the database servers, and the configuration changing method allows no two of the database servers to access the same data area. The configuration changing method changes the configurations of the database servers by specifying which data area is to be reallocated, judging whether or not the specified data area can be reallocated, and reallocating the specified data area without shutting down the database management system when it is judged that the specified data area can be reallocated.