Let K be a complete discrete valuation field of mixed characteristic (0, p) and GK the absolute Galois group of K. In this paper, we will prove the p-adic monodromy theorem for p-adic representations of GK without any assumption on the residue field of K, for example the finiteness of a p-basis of the residue field of K. The main point of the proof is a construction of (ϕ, GK )-module N ∇+ rig (V ) for a de Rham representation V , which is a generalization of Pierre Colmez' N