In order to realize an optical imaging probe whereby rotation unevenness, rotation transmission delay, and other problems are prevented in a rotation mechanism for rotary radiation of a light beam, constant-length scanning not only in a rotation direction but also in an axial direction is possible, and a three-dimensional observation image that is free of optical attenuation can be obtained without the need for an optical rotary joint, a first optical path conversion means for radiating a light beam in a substantially radial direction is disposed on a distal-end side of an optical fiber, and a second optical path conversion means for inclining an optical path by a minute angle with respect to a center of rotation from the distal end of the optical fiber and performing rotary radiation is disposed between the optical fiber and the first optical path conversion means. A structure is adopted whereby a rotary shaft of a second motor to which the second optical path conversion means is fixed is inserted, so as to be able to rotate in relative fashion, in an empty hole of a rotary shaft of a first motor to which the first optical path conversion means is fixed, and the optical fiber or a light beam radiated from the optical fiber penetrates through the empty hole of the rotary shaft of the second motor.Selon linvention, afin de réaliser une sonde dimagerie optique grâce à laquelle une rotation inégale, un retard de transmission de rotation, et dautres problèmes sont écartés dans un mécanisme de rotation destiné au rayonnement en rotation dun faisceau lumineux, un balayage à longueur constante est non seulement possible dans un sens de rotation mais également dans une direction axiale, et une image dobservation tridimensionnelle exempte daffaiblissement optique peut être obtenue sans avoir recours à un raccord rotatif optique, un premier moyen de conversion de trajet optique permettant le rayonnement dun faisceau lumineux dans une direction sensiblement radiale est disposé
