A seating furniture with a base member, an armrest member and first and second mounting devices that fix the armrest member to the base member in a horizontal direction. The first mounting device is slidable in parallel to an inner surface of the armrest member between an upper position and a lower position. When positioned in the upper position, an angled part of the first mounting device is rotatable relative to the armrest member between a locking position and a release position. In the locking position a first flange portion of the first mounting device is positioned such that an upper edge of the base member may be received into a gap between the first flange portion and the inner surface of the armrest member, whereas in the release position the first flange portion is positioned to release the upper edge of the base member from the gap.