To apply an arranged color pattern to a cement base material work even if the dimension of the work is not constant.

In the apparatus for manufacturing an exterior building material constituted by providing a feed device L1 for feeding the cement base material work 1A cut into a predetermined plate shape along a building material forming line L and a roll press device 5 for pressing the cement base material work 1A in its thickness direction on the building material forming line L and providing a sprinkling device 6 for sprinkling a color material 3 over the cement base material work 1A on the line downstream side of the roll press device 5 on the building material forming line L, a detection means S for detecting the position of the cement base material work 1A is provided between the roll press device 5 and the sprinkling device 6, and a control means T for indexing the reaching time of the cement base material work 1A to the place of the sprinkling device 6 from the detection result of the detection means S and controlling the operation of the sprinkling device 6 so as to sprinkle the color material 3 over the predetermined position of the cement base material work 1A is provided.