Opening detection device for an opening element such as a door or window (21, 22) including a module that is applied to an inner side of said opening element, characterised in that the module includes means for detecting movement (511, 520, 521) of said opening element, first presence detection means forming a conical beam defining a so-called trust perimeter encompassing an operating distance over which an operator operates the opening mechanism (23, 24) of the opening element on the first side of the opening element, second presence detection means for detecting a presence on a so-called mistrust perimeter circumscribed around the opening element and means for processing data from said detection means, for storage and for computation that are connected to said detection means, and wherein said processing means are configured to discriminate between: on the one hand, sequences of events that trigger an alarm, including: - a detection of a movement of the opening element by the movement detection means without the first presence detection means detecting an operator within said trust perimeter, - a detection of a presence, within the mistrust perimeter, by the second presence detection means without or before the first presence detection means detect the presence of an operator within said trust perimeter, and on the other hand, sequences of events that do not trigger an alarm, including: - a detection of an operator within the trust perimeter followed by a detection of movement of the opening element, - a detection of an operator within the trust perimeter surrounding a detection of presence within the mistrust perimeter; the module further including means for transmitting an alarm that can be activated by the processing means depending on the occurrence of either type of event. on the one hand, sequences of events that trigger an alarm, including: - a detection of a movement of the opening element by the movement detection means without the first presence detection means detecting an operator within said trust perimeter, - a detection of a presence, within the mistrust perimeter, by the second presence detection means without or before the first presence detection means detect the presence of an operator within said trust perimeter, and - a detection of a movement of the opening element by the movement detection means without the first presence detection means detecting an operator within said trust perimeter, - a detection of a presence, within the mistrust perimeter, by the second presence detection means without or before the first presence detection means detect the presence of an operator within said trust perimeter, and on the other hand, sequences of events that do not trigger an alarm, including: - a detection of an operator within the trust perimeter followed by a detection of movement of the opening element, - a detection of an operator within the trust perimeter surrounding a detection of presence within the mistrust perimeter; - a detection of an operator within the trust perimeter followed by a detection of movement of the opening element, - a detection of an operator within the trust perimeter surrounding a detection of presence within the mistrust perimeter; the module further including means for transmitting an alarm that can be activated by the processing means depending on the occurrence of either type of event.