A semiconductor device comprising: a bus master; a bus slave; a master interface (20A; 20B; 20C1) provided between the bus master and the bus (30A; 30B; 30C); a slave interface (40A; 40B; 40C) provided between the bus slave and the bus (30A; 30B; 30C); and a protocol conversion unit provided in the bus (30A; 30B; 30C), wherein the bus master outputs first data (RQa) generated based on the first protocol, wherein the master interface (20A; 20B; 20C1) includes a copy data generation unit for generating copy data (CRQa) by copying the first data (RQa), and a code generation unit for generating an error detection code (EDCa) based on the copy data (CRQa), wherein the master interface (20A; 20B; 20C1) is configured to output the first data (RQa), the copy data (CRQa), and the error detection code (EDCa) to the bus (30A; 30B; 30C), wherein the protocol conversion unit is configured to generate second data (RQb) by converting the first data (RQa) from the first protocol to the second protocol, wherein the slave interface (40A; 40B; 40C) is configured to receive the second data (RQb), the copy data (CRQa), and the error detection code (EDCa) from the bus (30A; 30B; 30C), wherein the slave interface (40A; 40B; 40C) includes an error detection unit for detecting an error of the copy data (CRQa) based on the error detection code (EDCa), a verification protocol conversion unit, and a comparator, and wherein the verification protocol conversion unit is configured to generate first verification data (VCRQb) by converting the copy data (CRQa) from the first protocol to the second protocol, and the comparator is configured to compare the second data (RQb) as second verification data (RQbT) with the first verification data (VCRQb), or the verification protocol conversion unit is configured to generate first verification data (VRQa) by converting the second data (RQb) from the second protocol to the first protocol, and the com parator is configured to compare the copy data (CRQa) as second verification data (RQbT) with the first verification data (VRQa). a bus master; a bus slave; a master interface (20A; 20B; 20C1) provided between the bus master and the bus (30A; 30B; 30C); a slave interface (40A; 40B; 40C) provided between the bus slave and the bus (30A; 30B; 30C); and a protocol conversion unit provided in the bus (30A; 30B; 30C), wherein the bus master outputs first data (RQa) generated based on the first protocol, wherein the master interface (20A; 20B; 20C1) includes a copy data generation unit for generating copy data (CRQa) by copying the first data (RQa), and a code generation unit for generating an error detection code (EDCa) based on the copy data (CRQa), wherein the master interface (20A; 20B; 20C1) is configured to output the first data (RQa), the copy data (CRQa), and the error detection code (EDCa) to the bus (30A; 30B; 30C), wherein the protocol conversion unit is configured to generate second data (RQb) by converting the first data (RQa) from the first protocol to the second protocol, wherein the slave interface (40A; 40B; 40C) is configured to receive the second data (RQb), the copy data (CRQa), and the error detection code (EDCa) from the bus (30A; 30B; 30C), wherein the slave interface (40A; 40B; 40C) includes an error detection unit for detecting an error of the copy data (CRQa) based on the error detection code (EDCa), a verification protocol conversion unit, and a comparator, and wherein the verification protocol conversion unit is configured to generate first verification data (VCRQb) by converting the copy data (CRQa) from the first protocol to the second protocol, and the comparator is configured to compare the second data (RQb) as second verification data (RQbT) with the first verification data (VCRQb), or the verification protocol conversion unit is configured to generate first verification data (VRQa) by converting the second data (RQb) from the second protocol to the first protocol, and the com parator is configured to compare the copy data (CRQa) as second verification data (RQbT) with the first verification data (VRQa).