A latch device, applied to selectively secure a latch plate device , wherein it comprises a latch plate with two latching holes , comprising: a housing unit , including a housing , which has a pressing hole and an insertion slot ; a disk unit , including a supporting rod positioned through the housing , and two vertical disks pivotally arranged to the supporting rod , around an outer perimeter of the two vertical disks being placed with a hook , a first engaging portion and a second engaging portion ; an electromagnetic lock unit , including two electromagnetic mechanisms fixed arranged inside the housing , two retractable bars respectively connected to the two electromagnetic mechanisms , and two electromagnetic latches respectively connected to the two retractable bars ; a pressing lock unit , including a press button slidingly connected to the press hole , and a button latch connected to the press button ; the latch device is characterized in that it comprises: a detecting unit , including two detectors , which are disposed inside the housing for detecting the position of the two electromagnetic latches ; wherein the two vertical disks can be moved between an unlatched position and a latched position, and when the two vertical disks are on the unlatched position, the latch plate can be inserted from the insertion slot and push the two vertical disks to the latched position; when the two vertical disks are on the latched position, the two electromagnetic latches are respectively latched with the two first engaging portions , and the button latch is concurrently latched with the two second engaging portions , so that the two vertical disks cannot either move or interfere respectively with the two latching holes , and the latch plate device can be secured to the latch device. a housing unit , including a housing , which has a pressing hole and an insertion slot ; a disk unit , including a supporting rod positioned through the housing , and two vertical disks pivotally arranged to the supporting rod , around an outer perimeter of the two vertical disks being placed with a hook , a first engaging portion and a second engaging portion ; an electromagnetic lock unit , including two electromagnetic mechanisms fixed arranged inside the housing , two retractable bars respectively connected to the two electromagnetic mechanisms , and two electromagnetic latches respectively connected to the two retractable bars ; a pressing lock unit , including a press button slidingly connected to the press hole , and a button latch connected to the press button ; the latch device is characterized in that it comprises: a detecting unit , including two detectors , which are disposed inside the housing for detecting the position of the two electromagnetic latches ; wherein the two vertical disks can be moved between an unlatched position and a latched position, and when the two vertical disks are on the unlatched position, the latch plate can be inserted from the insertion slot and push the two vertical disks to the latched position; when the two vertical disks are on the latched position, the two electromagnetic latches are respectively latched with the two first engaging portions , and the button latch is concurrently latched with the two second engaging portions , so that the two vertical disks cannot either move or interfere respectively with the two latching holes , and the latch plate device can be secured to the latch device. <EOS>