A bus control device (401a) includes a storage (408) that stores a transmission order of data pieces transmitted from a first node (402) to each second node (403); a sorter (413) that receives data pieces transferred from each second node toward the first node and refers to a predefined sorting rule to determine a sorting destination of each data piece; a buffer (409) that stores the sorted data pieces while classifying the sorted data pieces by the second node as a transmission source; and a connection controller (410) that refers to change permission/rejection information indicating whether or not an order is permitted to be changed while the data piece is transferred from each second node to the first node, and transmits data pieces, the order of which is not changed, from the buffer to the first node in the same order as the transmission order stored on the storage.