To provide a mold board holding device of a paving machine, which facilitates work for attaching/detaching a mold board and which can structurally reduce breakage by protecting a spring and the like.

Height adjusting means 30 for a mold board 20 includes: an upside bracket 31 that is provided on the side of the mold board 20; a downside bracket 32 that is provided on the side of a side frame 25; and an adjusting bolt member 36 that has an outer case 34 and an inner case 33 having a one-end side slidably inserted into the outer case 34 and that adjusts height by expanding/contracting a coiled spring 35.