A method of controlling an automatic door system, comprising: a first step (S2, S4) of driving a door panel by driving means to open a door opening in response to detection of presence of a human or an object in an activating sensor detection area by an indoor-side activating sensor or an outdoor-side activating sensor (12 or 16) associated with said door opening; a second step of judging, while said door opening is kept open in said first step, whether a human or an object is present or not in an auxiliary sensor detection area associated with a passing area of said automatic door system, through which a human or object passes, based on a light-reception indicative signal from an auxiliary sensor (26, 28) for keeping said door opening open when a human or an object is present in said auxiliary sensor detection area, said light-reception indicative signal being developed by light-receiving means of said auxiliary sensor (26, 28) when said light-receiving means receives light from light-emitting means of said auxiliary sensor (26, 28) which has passed said auxiliary sensor detection area; a third step of controlling said light-emitting means in a light-emitting state in which said light-emitting means is emitting light, to be placed in a light-emission stop state in which said light-emitting means stops emitting light, when it is judged from the judgment made in said second step that no human or object is present in said auxiliary sensor detecting area; a fourth step (S28, S30) of determining whether said light-receiving means is developing said light-reception indicative signal or not when said light-emitting means is in said light-emission stop state, and judging that said auxiliary sensor (26, 28) is out of order when said light-reception indicative signal is being developed; a fifth step of placing said light-emitting means in said light-emitting state when it is judged in said fourth step that said light-reception indicative signal is not being developed; a sixth step (S34, S30) of judging whether or not said light-receiving means is developing the light-reception indicative signal when said light-emitting means is placed in said light-emitting state in said fifth step, and determining that said auxiliary sensor (26, 28) is operating in order when it is judged that said light-reception indicative signal is being developed and that said auxiliary sensor (26, 28) is out of order when it is judged that said light-reception indicative signal is not being developed; and a seventh step of causing said driving means to drive said door panel to close said door opening when it is judges in said sixth step that said auxiliary sensor (26, 28) is operating in order. a first step (S2, S4) of driving a door panel by driving means to open a door opening in response to detection of presence of a human or an object in an activating sensor detection area by an indoor-side activating sensor or an outdoor-side activating sensor (12 or 16) associated with said door opening; a second step of judging, while said door opening is kept open in said first step, whether a human or an object is present or not in an auxiliary sensor detection area associated with a passing area of said automatic door system, through which a human or object passes, based on a light-reception indicative signal from an auxiliary sensor (26, 28) for keeping said door opening open when a human or an object is present in said auxiliary sensor detection area, said light-reception indicative signal being developed by light-receiving means of said auxiliary sensor (26, 28) when said light-receiving means receives light from light-emitting means of said auxiliary sensor (26, 28) which has passed said auxiliary sensor detection area; a third step of controlling said light-emitting means in a light-emitting state in which said light-emitting means is emitting light, to be placed in a light-emission stop state in which said light-emitting means stops emitting light, when it is judged from the judgment made in said second step that no human or object is present in said auxiliary sensor detecting area; a fourth step (S28, S30) of determining whether said light-receiving means is developing said light-reception indicative signal or not when said light-emitting means is in said light-emission stop state, and judging that said auxiliary sensor (26, 28) is out of order when said light-reception indicative signal is being developed; a fifth step of placing said light-emitting means in said light-emitting state when it is judged in said fourth step that said light-reception indicative signal is not being developed; a sixth step (S34, S30) of judging whether or not said light-receiving means is developing the light-reception indicative signal when said light-emitting means is placed in said light-emitting state in said fifth step, and determining that said auxiliary sensor (26, 28) is operating in order when it is judged that said light-reception indicative signal is being developed and that said auxiliary sensor (26, 28) is out of order when it is judged that said light-reception indicative signal is not being developed; and a seventh step of causing said driving means to drive said door panel to close said door opening when it is judges in said sixth step that said auxiliary sensor (26, 28) is operating in order.