This paper addresses the problem of detecting characters in natural scene image. How to correctly discriminate character/non-character is also a very challenging problem. In this paper, we propose new character/non-character discrimination technique using the rotation angle of characters to improve character detection accuracy in natural scene image. In particular, we individually recognize characters and estimate the rotation angle of those characters by our previously reported method and use the rotation angle for character/non-character discrimination. As the result of the character recognition experiment evaluating 50 alphanumeric natural scene images, we have confirmed the accuracy improvement of precision and -measure by 9.37 % and 4.73 % respectively when compared to the performance with previously reported paper.