Abstract: A detector device is provided, in particular for detecting faulty needles or closed needle latches in a knitting machine with latch type needles, consisting of a non-electrically-conductive feeler which is normally resiliently urged into contact with the upper parts of the needle hooks, and an electrically-conductive probe which normally does not contact the needles but passes through the needle hook openings as relative movement of the needles past the detector takes place. However, if a needle latch is closed the probe makes contact with it and also if the needle hook is broken or bent the feeler is permitted to move laterally thereby enabling the probe to contact the faulty needle, contact of the probe with a needle completing an electrical circuit which signals a needle fault. For circular knitting machines in which the needles travel past the detector, the detector is associated with a controller that stops the machine when the faulty needle reaches a particular position in the needle travel path.