A multiplier device comprising hold means for holding the result of addition, block product means for producing k block products each having 2n bits, where n is an integer equal to or greater than 2, the k block products being formed by multiplying each block by n bits, k blocks being obtained by dividing a multiplicand at intervals of n bits from the least significant bit of the multiplicand, and adder means for adding two groups of block products to the output of the hold means, the two groups of block products consisting of alternate block products out of the k block products from the block product means.