A VLIW processor which has an instruction set whose size is reduced so that a small number of bits are necessary to specify registers is provided. The VLIW processor 10 comprises the register file 12, the first-the third operation units 14a-14c and the like, and executes the very long instruction word. And, the very long instruction word includes the register specifying field which specifies a least one of the registers in the register file 12 and a plurality of instructions. The operand of each instruction has the bits, src1 src2 and dst, indicating whether or not the registers specified by the register specifying field are to be used as the source register and the destination register.