Abstract: A code converting method in which a multivalue signal x.sub.i sampled at a sampling period of mT, where m (an even number) equals 2.sup.n (n being integer) and x.sub.i is non-negative integer not greater than m, is received and subjected to density conversion to be delivered out in the form of a train of m binary signals sampled at a sampling period of T. A Z-transform Y(Z) of the binary signal to be delivered out is expressed as, ##EQU1## where q.sub.i+1 .ident.q.sub.i +X.sub.i+1 +m, and mod 2; q.sub.o =0 and where H(x.sub.i, q.sub.i, Z) represents a polynomial of the order related to Z.sup.-1 not greater than (m-1) which has non-zero terms having each a coefficient of 1(one) and which satisfies H(k, q.sub.i, 1)=k, H(k, q.sub.i, Z)=Z.sup.-(m-1) H(k,q.sub.i,1/Z) and H(k,0,Z)=H(k,1,Z) for k being an even number, and H(k,0,Z)=Z.sup.-(m-1) H(k,1,1/Z) for k being an odd number.