The present invention addresses the problem of providing a cutting blade that satisfies both stable shape accuracy and workability, and that enables oblique cuts to be minimized. A blade tip section (7), which is the cutting implementation section of this flat blade-shaped cutting blade (1) has: a left blade surface (9a) and a right blade surface (9b), which are sloped in such a manner as to approach each other from the left and right surfaces of a base section (5); and a blade tip (11) that is formed in such a manner as to connect the left blade surface (9a) and the right blade surface (9b), and has a convex curved surface. The shortest distance between the point of intersection between two straight lines (13a, 13b) that lie along the left blade surface (9a) and the right blade surface (9b), and the blade tip (11) is 1 [mu]m to 10 [mu]m. The length of the blade tip (11) differs on the left and right with respect to a center line (21), with the difference being 1 [mu]m to 20 [mu]m. Moreover, the interior angle of the angle of intersection between the two straight lines that lie along the left and right blade surfaces is 4 degrees to 60 degrees.