Abstract: Chair comprising a support element, a seat and a backrest, the seat consisting of a foremost portion being rigidly connected to the support element and of a rear portion being pivotally connected to the support element and being supported by an arm at some distance from its pivot, said arm being positioned beneath the seat and carrying the backrest. Said arm being pivotally connected to the support element and being biased by a progressively acting spring member towards the position which the rear seat portion and the backrest are occupying in the unloaded state.