An angle measuring device 2 is configured to detect an angle formed between a measured line LX connecting a first position PL and a second position PR and a predetermined reference plane. The angle measuring device 2 includes: a case 10; a first pointing mechanism 30L for pointing the first position PL; a second pointing mechanism 30R for pointing the second position PR; moving mechanisms 60L and 60R that allow at least one of the first and second pointing mechanisms 30L and 30R to be movable; and a turning member angular scale mark 72 that indicates a moved amount of at least one of the first and second pointing mechanisms 30L and 30R by the moving mechanisms 60L and 60R. The moving mechanisms 60L and 60R move the first pointing mechanism 30L and the like so that a line segment connecting the first pointing mechanism 30L and the second pointing mechanism 30R includes the measurement reference plane or becomes parallel to the measurement reference plane.