To provide an installation angle adjusting type washer for precisely joining an object to be installed and an installation object by a bolt, even if a normal of an abutting part of a bolt head part of the object to be installed or an abutting part of a nut is inclined in a specific range to the axis of a bolt shaft inserting hole formed in the abutting part.

This installation angle adjusting type washer is composed of a packing member for forming the bolt shaft inserting hole in a central part and forming a base end part bottom surface as a seat surface for abutting on the abutting part of the object to be installed and a case for forming the bolt shaft inserting hole in a central part of an end surface wall, forming the end surface wall as a pressure receiving surface for abutting on the bolt head part or the nut and storing the packing member. A base end part of the packing member is projected from a peripheral sidewall of the case, and is formed so that the base end part bottom surface of the peripheral sidewall and the base end part bottom surface of the packing member are inclined to the normal erected in the abutting part of a fastening object.