A data transfer control device includes: an interface circuit to which data of which one data unit is K bits is input through an interface bus; and a link controller which generates a packet transmitted through a serial bus. The link controller includes: a data formatter which generates (N×I)-byte packed data containing M pieces of (K+L)-bit data obtained by adding L bits of dummy data to the K-bit data, the data formatter generating the packed data in which L and M are variably set corresponding to K; and a packet generation circuit which generates a packet in which the packed data is inserted in a data field.