To provide a ruler effective for a correction tape for correcting wrong letters of documents, etc., by superimposingly transferring an opaque film on characters.

Tape cutting portions 2a, 2b are provided as being extended upward at the right end of a longitudinal ruler main body 1 in the drawing, and downward at the left end thereof respectively, and the end peripheries 3a, 3b faced to the inside of each tape cut portions 2a, 2b are shaped into a knife-edge by gradually reducing its thickness. A correction tape feed device is moved along any one of rectilinear straight ruler portions 1a, 1b of the main body 1 as a guide, to be superimposed on wrong letters for transferring an opaque film and correcting the wrong letters, and when reaches any one of the tape cut portions 3a, 3b, the tip end of the correction tape feed device is moved apart from the paper, thus cutting the distal end of the correction tape neatly rectilinearly. The right-handedness uses a combination of the straight ruler portion 1a and tape cut portion 3a, and the left-handedness uses a combination of the straight ruler portion 1b and tape cut portion 3b. In this fashion, a ruler with diversified uses can be obtained including a figure-drawing template 4 as well as a length measuring scale 5.