A portable ladder has two stiles interconnected by rungs. The ladder is provided with a stand off device, including two stand off arm assemblies, each being telescopically inserted into a receiving space. Each stand off arm assembly has a base part and a stand off arm interconnected by a hinge that allows the stand off arm to be pivoted between a position in alignment with the base part and an angled stand off position. The stand off arm assemblies are each configured such that—in extended position—the hinge is located outside the receiving space with the base part being located within said receiving space, and also such that—in retracted position—the base part, the hinge, as well as at least a portion of the stand off arm are located within the receiving space.