A liquid injector comprises a contact member comprising a tube body including an opening located at a distal end of the contact member an inner structure body comprising: a cylindrical main body and a hollow needle, wherein the inner structure body is movable to (i) a first position at which a needle tip is located proximal of the opening, and (ii) a second position at which the needle tip is located distal of the opening and a regulating member detachably mounted on the inner structure body, including a fixing portion to be fixed to the contact member at the second position. When the inner structure body moves to the second position from the first position and returns to the first position again, the regulating member is fixed to the contact member with the fixing portion at the second position, separated from the inner structure body, and stays at a position at which the regulating member covers at least part of an area of the opening.
