Provided is a medical fluid administration device wherein it is possible to detect, with a simpler configuration, that a syringe is set in the correct position. An administration head (110) mounted with a syringe assembly (200) in a detachable manner is provided with a clamper (140) which immobilizes the syringe assembly (200) by enclosing the entire circumference of the cover flange (271) of the syringe assembly (200). The clamber (140) is provided with a base member, a flange holding member which is supported by the base member in a rotatable manner, and an engagement structure which locks the flange holding member in a closed position. The base member is provided with a proximity sensor which detects the syringe assembly (200) placed on the clamper (140), and a proximity sensor which detects that the flange holding member is locked in a closed position.
