1. A management server, which is coupled to a computer system including a plurality of computers, and which manages a tenant pattern being information for forming a tenant being an application system for executing a predetermined application by using computer resources within the computer system, the tenant pattern including: a configuration item including a parameter necessary for generation of the tenant and a determination method for a value of the parameter; and an ID pool for storing the value assigned to the parameter at a time of the generation of the tenant, the management server comprising: a processor; a memory coupled to the processor; and a network interface coupled to the processor, the management server having: first pattern parts information for managing the configuration item as a pattern part that forms the tenant pattern; validation rule information for storing a detail of validation processing for a composition of the tenant pattern generated by using at least one the pattern part; and tenant pattern information for storing the composition of the tenant pattern generated by using the at least one the pattern part, the management server further comprising: a tenant pattern generation unit for generating the tenant pattern by using the pattern part; a tenant designing unit for designing a composition of the tenant by using the tenant pattern, and generating a configuration detail for actually building the tenant on the computer system based on the designed composition of the tenant; and a validation execution unit for executing the validation processing for one of the tenant pattern and the configuration detail based on the validation rule information.