Goryeong Yangjeondong Petroglyph on the joint face of the bedrock (6m in width, 3m in height) composed of the green sandstone has circles and shield pattern sculptures. The rock is mainly composed of quartz, feldspar, chlorite, illite and calcite with the clay minerals. These clay minerals occur as pore lining, replacement of component and pore fillings. Investigated the weathering aspects including the connection between soluble salt and rock weathering and the stability of the bedrock with petroglyphs. The Major deterioration aspect are grain peel-off, surface exfoliation, cracks and damage. And the bedrock where the joints and cracks advance is interpreted with the fact that has the possibility of the falling rock. For conservation, adhesive need to cover crack and damage and consolidation is necessary in the surface which becomes weak.