The disclosed invention improves the transfer efficiency of a bus transfer device. A semiconductor device includes a bus transfer device including a read data transfer path which can transfer read data having an n-bit width at a maximum. If first read data and second read data corresponding respectively to a first transaction and a second transaction have a total bit width of n bits or less, the bus transfer device can simultaneously transfer data obtained by unifying the first read data and the second read data, first transaction identification information, and second transaction identification information through the read data transfer path.