1. a task processing apparatus, comprising: an allocator to allocate a plurality of tasks to a plurality of servers, each task being allocated to a different server; an executor to execute the plurality of tasks through the plurality of servers; a task selector to select a task, which is allocated to an existing allocation server from among the plurality of servers, to be parallel processed by multiple servers from among the plurality of servers, the task being selected from among the plurality of tasks based on predetermined task selection information when a task execution is completed and an idle server occurs in the plurality of servers, wherein the predetermined task selection information to be parallelized comprises rule information used to select a task having a relatively large number of child nodes from the plurality of tasks and a relatively small prediction interval up to a child node from the plurality of tasks; a separator to separate the selected task into a first task and a second task applying a parallelization level of the first task and second task; a controller to control the first task to be allocated to the existing allocation server and the second task to be allocated to the idle server in order to parallel process the first and second tasks; and a combiner to combine the first task and the second task into a single task, wherein the allocator allocates the combined single task to the existing allocation server.