The comparator for signals which are coded in a given number system and represented by a fluid pressure comprises a first and a second rigid block pierced by transverse ducts which are arranged in a row and to which is applied a fluid pressure representing respectively a first and a second input signal, at least one elastic membrane which separates the two blocks, a first and a second discharge duct pierced in the second block on each side of the transverse ducts, means actuated by the pressure representing the second signal so as to deform the elastic membrane and to permit propagation of said pressure in the direction of the two output ducts, and means actuated by the pressure representing the first signal in order to deform the elastic membrane and to prevent propagation of the pressure representing the second signal beyond the duct corresponding to the first signal.