This liquid-drug administration device has: an actuator (11) gears (13, 15, 17) driven by the actuator (11) an output shaft (19) for causing a plunger (103) to slide inside a syringe (101) for housing a liquid drug, and provided along the axis of rotation of one (17) of the gears and a closure detection unit (20) for detecting the closure of a liquid-drug channel through which administration from the syringe (101) occurs, and provided between the actuator (11) and the output shaft (19). The closure detection unit (20) is equipped with: a fixed slit disc (21) having a slit (s1) in the disc surface and provided so as to rotate in synchronization with the rotation of the actuator (11) a slit disc (23) having a slit (s2) in the disc surface, and assembled relative to the fixed slit disc (21) in a state of overlap on the same axis as that of the fixed slit disc (21) and so as to rotate in synchronization with the rotation of the actuator (11) and an elastic member (25) for delaying the rotation of the slit disc (23) relative to the rotation of the fixed slit disc (21), according to an increase in the back pressure applied to the slit disc (23), and provided so as to connect the fixed slit disc (21) and the slit disc (23) to one another.La présente invention concerne un dispositif dadministration de médicament liquide qui comprend : un actionneur (11) des engrenages (13, 15, 17) entraînés par lactionneur (11) un arbre de sortie (19) pour amener un piston (103) à coulisser à lintérieur dune seringue (101) pour contenir un médicament liquide, et disposé le long de laxe de rotation de lun (17) des engrenages et une unité de détection de fermeture (20) pour détecter la fermeture dun canal de médicament liquide par lintermédiaire duquel ladministration depuis la seringue (101) est effectuée, et disposée entre lactionneur (11) et larbre de sortie (19). Lunité de détection de fermeture (20) est équipée de : un disque à fente fixe (21) ayant une fente (s1) dans la surface du d
