1. A command execution device, comprising: a behavior type decision unit which decides a behavior type for data based on a content of a data input/output operation and a data processing command, wherein the behavior type comprises at least one of a sequential read and a sequential write; a command storage unit which stores the data processing command in a command queue, wherein a priority level is created for the data processing command based on a priority level in setting information set in advance for the behavior type; a command execution unit which executes the data processing command stored in a section of the command queue based on the priority level; and a generation unit which controls the data input/output operation for the behavior type and generates, based on the setting information set before the initiation of data processing, a transmit buffer that stores transmit data resulting from the data input/output operation, and a receive buffer that stores receive data resulting from the data input/output operation; wherein the setting information further comprises at least one of a data size of the transmit data resulting from the data input/output operation, a priority level of transmit processing resulting from the data input/output operation, a data size of receive data resulting from the data input/output operation, and a priority level of receive processing resulting from the data input/output operation.