A device for detecting the level of a liquid in a container comprises a substrate (4) on which discrete resistors (5) are mounted and are interconnected by a plurality of metallized regions (6). A movable floating body (8) has electrical contact means (11, 12) which can interact with comb-shaped metallized regions (7) which are connected electrically to the resistors (5) in different ways according to the position of the float (8) so that the electrical contact means (11, 12) detect different resistance values in dependence on the level of the liquid in the container.