A cutting angle display device for use in a miter saw for displaying an optimum cutting angle of a construction member and a miter saw having the cutting angle display device. A first construction member having a first cut end will be installed on a first wall, and a second construction member having a second cut end will be installed on a first wall in such a manner that the first and second cut ends are spliced with each other at a corner portion between the first and second wall. To provide the first and second cut ends with the optimum cutting angle, an angle between the first and second wall is input, and a microcomputer selects the optimum cutting angle based on the input angle, and the selected optimum cutting angle is displayed. A user can cut the construction member by means of the miter saw with the displayed optimum cutting angle.