The object of the present invention is to obtain a high quality single crystalline diamond that has less distortion and large area suitable for semiconductor device substrates or an optical component material. The present invention is a single crystalline diamond produced by chemical vapor deposition, wherein, when a linear polarized light which is composed of two linear polarized lights perpendicular to each other is introduced into one main face of the single crystalline diamond, a maximum value of a retardation between the two linear polarized lights perpendicular to each other which come out from an opposite main face is not more than 50 .mu.m at maximum per a thickness of 100 .mu.m across an entire of the single crystalline diamond, and also a method for producing the diamond.