Fällbart armstöd för ett fordonssäte

An armrest for a vehicle seat includes a seat cushion and a backrest. The armrest is intended to be turned around a pivot axis between a first active position and a second folded-away position. The armrest includes an upper part, which in the active position is positioned with its longitudinal axis substantially parallel to a substantially vertical plane through a side surface constituting an outer edge surface of the vehicle seat and intended to support a user's forearm, and at least one lower part provided with a fixing device for attaching the upper part to the vehicle seat. The lower part includes a linking mechanism arranged for setting the upper part in a transverse direction between a first position outside the side surface and an adjustable second position, and a locking device that is arranged to activate a catch that locks the upper part in a set position after it has been moved to the second position. A vehicle seat provided with an armrest and to a vehicle including an armrest are also provided.