A method of processing information, includes: creating threads for respective input data streams, and switching them for processing, the threads each being for applying predetermined processing to an input data stream and storing the resulting intermediate data into a buffer; and reading multiple pieces of the intermediate data from the respective corresponding buffers to output multiple pieces of output data in parallel. The switching for processing includes: detecting the amount of intermediate data that is stored and yet to be read in the buffers when starting processing the threads; and stopping processing of the thread when the amount of the intermediate data thereof exceeds a set value, and switching processing to other threads.