An eyeglass lens processing apparatus for processing a periphery of a lens, comprising: lens rotating means for rotating a pair of lens chuck shafts that hold an eyeglass lens; processing tool rotating means (300, 420) for rotating a processing tool rotating shaft (161a, 400a) to which a processing tool (168, 400) for processing the periphery of the lens is mounted; moving means for moving about the lens chuck shafts or the processing tool rotating shaft as a moving shaft in an axis-to-axis direction in which an axis-to-axis distance between the lens chuck shafts and the processing tool rotating shaft is changed; a waterproof cover provided with a first elongated hole (75L, 75R) through which the moving shaft is inserted, the waterproof cover configuring a processing chamber; a shield unit provided in the waterproof cover for preventing grinding water from leaking out of the first elongated hole, the eyeglass lens processing apparatus characterized by the shield unit being configured to be rotated in response to movement of the moving shaft, wherein the shield unit includes a first rotating plate (76, 81) rotatably held by the waterproof cover, the first rotating plate is provided with a second elongated hole (76b, 81a) through which the moving shaft is inserted and which enables the moving shaft to move between a first position at which the moving shaft approaches a rotational center of the first rotating plate and a second position (PC1, PC2) at which the moving shaft is separated from the rotational center of the first rotating plate during the movement of the moving shaft in the axis-to-axis direction, and the shield unit further includes a moving member (77, 82, 83) which is connected to the moving shaft and is configured to block a gap that otherwise occurs due to an overlap of the first elongated hole and the second elongated hole. lens rotating means for rotating a pair of lens chuck shafts that hold an eyeglass lens; processing tool rotating means (300, 420) for rotating a processing tool rotating shaft (161a, 400a) to which a processing tool (168, 400) for processing the periphery of the lens is mounted; moving means for moving about the lens chuck shafts or the processing tool rotating shaft as a moving shaft in an axis-to-axis direction in which an axis-to-axis distance between the lens chuck shafts and the processing tool rotating shaft is changed; a waterproof cover provided with a first elongated hole (75L, 75R) through which the moving shaft is inserted, the waterproof cover configuring a processing chamber; a shield unit provided in the waterproof cover for preventing grinding water from leaking out of the first elongated hole, the eyeglass lens processing apparatus characterized by the shield unit being configured to be rotated in response to movement of the moving shaft, wherein the shield unit includes a first rotating plate (76, 81) rotatably held by the waterproof cover, the first rotating plate is provided with a second elongated hole (76b, 81a) through which the moving shaft is inserted and which enables the moving shaft to move between a first position at which the moving shaft approaches a rotational center of the first rotating plate and a second position (PC1, PC2) at which the moving shaft is separated from the rotational center of the first rotating plate during the movement of the moving shaft in the axis-to-axis direction, and the shield unit further includes a moving member (77, 82, 83) which is connected to the moving shaft and is configured to block a gap that otherwise occurs due to an overlap of the first elongated hole and the second elongated hole.