A computer system includes a plurality of task processing nodes capable of executing tasks and a task management node which determines which a task processing node to allocate a new task and each task processing nodes includes a memory capable of caching data to be used by an allocation task which is a task allocated to the task processing node. The task management node stores task allocation history information including a correspondence relationship between the allocation task and the respective task processing node A CPU of the task management node determines a degree of similarity between the new task and the allocated task, determines the task processing node to which the new task should be allocated from the task processing nodes included in the task allocation history information based on the degree of similarity, and allocates the new task.