A half-latch and full-latch detecting device for an automotive slide door operating system is shown, which comprises:a power feeding start position detecting switch which becomes operated when the door under closing movement comes to a given position just before a half-latch position of the door at which half-latch position a latch plate of a door lock device assumes a half-latch position;a latch plate position detecting switch having a probe which is contactable with an open lever when the open lever is pivotally moved, the open lever being rotatable with a latch pawl which can latch the latch pawl at the half-latch and full-latch positions;a counter circuit electrically connected to both the power feeding start position detecting switch and the latch plate position detecting switch, the counter circuit counting the number of times by which the open lever contacts the probe of the latch plate position detecting switch after the power feeding start position detecting switch is operated; anda judging circuit for judging that the latch plate assumes the half-latch position when the counter circuit counts the number "one" and judging that the latch plate assumes the full-latch position when the counter circuit counts the number "two".