A liquid ejecting apparatus informs a user when an ink tank is substantially mechanically attached so as to prevent an attaching operation from being stopped by a user before completion of attachment of the ink tank. A board is provided with a light emitter, and a control unit for controlling the light emitter according to a conductive state between an electrode and a counterpart electrode. The liquid tank is moved by force P, a second engaging portion is locked to a second locking portion, and then, the liquid tank is attached to a holder at an attachment completion position. The non-conductive state between the electrodes is changed to a conductive state before the second engaging portion engages with the second locking portion, and then, the liquid tank is fixed at the attachment completion position during movement in a reverse direction after the liquid tank passes the attachment completion position.