To manufacture a PC panel which is lightweight, shows durability, weatherability and strength required for an exterior wall material and includes a good textured exterior surface.

The surface layer (2) with a density of 2.3 of a hardened concrete body is formed by pouring a mixture obtained by mixing a hydraulic cement, a colored aggregate, a pigment, and water on a table vibrator (8). A back layer (3) with a density of 2.1 is formed as the back layer for the surface layer by pouring a lightweight concrete on the surface layer after the table vibrator is stopped and a prescribed drying and curing time includes elapsed. The concrete formed body (21) having a double-layered structure is released from the frame. The exterior surface (4) is surface-treated. Part of the colored aggregate is exposed on the exterior surface.