A high-pressure washing liquid ejecting washing apparatus comprises a bar-shaped holder; and a plurality of high-pressure washing liquid ejecting nozzles arranged at constant intervals along a longitudinal direction of the bar-shaped holder, the holder being supported at both sides in a longitudinal direction thereof such that the holder is rotatable around its longitudinal axis, the holder being reciprocatingly rotated around the longitudinal axis within a predetermined rotational angle and the ejecting nozzles ejecting a high-pressure washing liquid to a washed surface of an object in a single straight-line shape to wash the object while the object is conveyed at a constant speed with respect to the holder, wherein the holder has a length which is not less than a length across the object and is disposed such that the holder is orthogonal to a direction in which the object is conveyed or is tilted with respect to the direction in which the object is conveyed, when viewed from a normal line direction of the washed surface.