To provide a fixing device for mounting a substrate for painted wall/painted roof for preventing the painted wall/painted roof from peeling off easily due to vibration of earthquake.

This fixing device for mounting the substrate for the painted wall/painted roof on a skeleton has a mounting hole whose thickness in the direction of passing through of the mounting hole is 9 to 20 mm, has area of a face being vertical for the direction of passing through of the mounting hole and being in contact with the substrate of 3 to 15 cm2, and has area of an opposing face of 5 to 20 cm2.