To stably manufacture crushed sand of high quality by making it possible to easily supplement a proper amount of medium stones when the medium stones are abraded and reduced, and by making it possible to supply raw sand and water so as to adjust their mixing ratio to the most suitable ratio.

A crushed sand manufacturing device for concrete is proved with an agitation drum main body 4 of which the inside is made to be an agitation room 2, and which stores the medium stones 3, a supply-side small-diameter drum 5 connected to the supply side of the agitation drum main body 4, a discharge-side small-diameter drum 6 connected to the discharge side of the agitation drum main body 4, a support structure 7 rotataby supporting the agitation drum main body 4, the supply-side small- diameter drum 5, and the discharge-side small-diameter drum 6, a driving device 8 driving these devices so as to rotate them, a raw sand supply device 14 in which the raw sand 9 is stored, a medium stone supplement device 19 in which the medium stones 3 are stored, and a water supply device 21 supplying a proper amount of water 20 to the raw sand fed into the supply-side small-diameter drum 5. In the agitation room 2, a feeding blade 23 and a returning blade 24, and an agitation projecting streak 25 are installed.