  In this paper the notion of the rigid frame of reference within special
relativity is analysed. Three definitions of rigidity are formulated. By using
several examples of non-inertial frames, it is shown that these definitions are
not equivalent. It is also shown that so called M\"oller rigid non-inertial
frames are locally rigid, but do not exhibit global rigidity. The physical
meaning of this phenomenon is discussed, as well as its relation to the
non-Euclidean nature of space in non-inertial frames of reference. (russian
version)
