A liquid administration device includes: a cylindrically-shaped cylindrical body configured to be filled with liquid a needle tube configured to have a tip side needle tip, to be provided at the tip side of the cylindrical body, and to be communicable with the cylindrical body a gasket configured to be capable of sliding within the cylindrical body an operation member configured to perform pressing operation to discharge the liquid from the needle tube by pressing the gasket toward the tip direction a restricting member configured to be capable of restricting the pressing operation and a cover member configured to be capable of moving to a first position, in which the tip side needle tip is covered, and to a second position, in which the tip side needle tip is exposed, wherein a protrusion part is formed protrudedly on the restricting member, and a groove, into which the protrusion part is inserted, is formed on the operation member, the groove having a longitudinal groove formed along the same direction as an operation direction during the pressing operation, and a lateral groove communicating with the longitudinal groove and formed along the direction perpendicular to the operation direction when the cover member is in the first position, the protrusion part is positioned in the lateral groove and restricts the pressing operation, and when the cover member moves from the first position to the second position, the protrusion part moves from the lateral groove to the longitudinal groove in conjunction with the movement, thereby the pressing operation is made possible.
