Because of its interesting applications in coding theory, cryptography, and algebraic combinatorics, in recent decades a lot of attention has been paid to the algebraic structure of the ring of polynomials R[x], where R is a finite commutative ring with identity.Motivated by this popularity, in this paper we determine when R[x] is a principal ideal ring.In fact, we prove that R[x] is a principal ideal ring if and only if R is a finite direct product of finite fields.
