A virtual machine system that includes a plurality of processors (1901, 1902, 1903, 1904, 1905, 1906) and executes a plurality of virtual machines (411, 412, 413, 414), each processor (1901, 1902, 1903, 1904, 1905, 1906) being placed in any of: a first state in which the processor (1901, 1902, 1903, 1904, 1905, 1906) operates with a power supply; a second state; and a third state in which the processor (1901, 1902, 1903, 1904, 1905, 1906) is not in operation without any power supply, the virtual machine system comprising an allocation unit (2242; 3501) configured to allocate each virtual machine (411, 412, 413, 414) to any processor (1901, 1902, 1903, 1904, 1905, 1906) that is supplied with power, wherein allocating a virtual machine to a processor in the second state causes the processor to be placed in the first state; and a power supply unit (1911; 3502); in said second state, the processor (1901, 1902, 1903, 1904) operates with a power supply lower than in the first state, said power supply unit (1911; 3502) configured to, when the allocation unit (2242; 3501) allocates a virtual machine (411, 412, 413, 414) to a processor that is in the second state and does not have any virtual machine (411, 412, 413, 414) allocated thereto, and at least two processors are in the third state, supply power to at least one and less than all of the processors in the third state so as to cause the at least one and less than all of the processors to be placed in the second state, and maintain a remaining one or more of the processors in the third state, characterized in that the plurality of processors include type 1 processors (1904, 1905, 1906) and type 2 processors (1901, 1902, 1903) having a lower processing capability and a lower power consumption than the type 1 processors (1904, 1905, 1906), for each virtual machine (411, 412, 413) allocated to either type of processors between the type 1 processors (1904, 1905, 1906) and the type 2 processors (1901, 1902, 1903), when processing of the virtual machine (411, 412, 413) satisfies a predetermined condition, the allocation unit reallocates the virtual machine satisfying the predetermined condition to one of the other type of processors, when the allocation unit allocates a virtual machine (411, 412, 413) to a type 1 processor that is in the second state and does not have any virtual machine (411, 412, 413) allocated thereto, and at least two type 1 processors are in the third state, the power supply unit supplies power to at least one and less than all of the type 1 processors in the third state so as to cause the at least one and less than all of the type 1 processors to be placed in the second state, and maintains a remaining one or more of the type 1 processors in the third state, and when the allocation unit allocates a virtual machine (411, 412, 413) to a type 2 processor that is in the second state and does not have any virtual machine (411, 412, 413) allocated thereto, and at least two type 2 processors are in the third state, the power supply unit supplies power to at least one and less than all of the type 2 processors in the third state so as to cause the at least one and less than all of the type 2 processors to be placed in the second state, and maintains a remaining one or more of the type 2 processors in the third state.