To manufacture an external facing concrete unit which has tiles arranged accurately at accurate joint intervals while preventing penetration of concrete into joints.

The tiles (t) are disposed downward at positioning sections 1a of a positioning sheet 1 and adhered thereto temporarily by a double-sided adhesive tape, and the positioning sheet 1 holding the tiles (t) is arranged in a form 2. Then, the concrete 3 is placed in the form 2. After the concrete is set, the form 2 is removed and the positioning sheet 1 is peeled off. Herein, a connecting male piece on the side being in contact with the side wall 2a of the form 2 is cut off beforehand and the adjacent positioning sheet 1 are arranged mutually in such a manner that the side having the connecting male piece formed and the side formed to be a recessed part 1d come into contact with each other so that the mutual sheet members may not be put on each other at the boundary and that a joint extending from a section wall 1b may be fitted in and connected to the end part of an adjacent section wall 1b. Thereby, the concrete is prevented from getting into the joint when it is placed.