An optical coherence tomography device comprising: split beam generating means (61; 111) for splitting light emitted from a single wavelength-swept laser light source into at least four split beams and outputting the split beams; object light beam irradiating means (64; 106) for irradiating different positions of a measurement target with object light beams (107a, 107b; 107c) being at least two of the at least four split beams through a mechanism capable of changing a position of each of the object light beams (107a, 107b; 107c) on the measurement target; reference beam irradiating means (63; 104) for irradiating a reference beam mirror (66; 108) with at least two of the at least four split beams that are not the object light beams (107a, 107b; 107c), as reference beams (R41, R42; R43); and optical spectrum data generating means (68; 109) for acquiring depth-direction structural data about the measurement target from interference light (R51, R52, R61, R62; R53, R63) to be acquired by causing each of the reference beams (R41, R42; R43) reflected by the reference beam mirror (66; 108) to interfere with a corresponding one of the object light beams (R31, R32; R33) reflected or scattered by the measurement target, characterized in that the object light beam irradiating means (64; 106) includes a front lens system being set in such a way that the object light beams (107a, 107b; 107c) are collimated and cross at one point, an optical beam scanner being placed at a position in which the object light beams (107a, 107b; 107c) cross, and a rear lens system (203, 204) that causes the object light beams (107a, 107b; 107c) passing through the light beam scanner to be condensed on the measurement target, and changes, on the measurement (107a, 107b; 107c) target, a position of each of object light beams (107a, 107b; 107c) with which different positions of the measurement target are irradiated, and wherein the optical coherence tomography device further comprises a mechanism for causing a lens of the rear lens system (203, 204) for the object light beam irradiating means (64; 106) to move in a direction parallel to a depth direction of the measurement target. split beam generating means (61; 111) for splitting light emitted from a single wavelength-swept laser light source into at least four split beams and outputting the split beams; object light beam irradiating means (64; 106) for irradiating different positions of a measurement target with object light beams (107a, 107b; 107c) being at least two of the at least four split beams through a mechanism capable of changing a position of each of the object light beams (107a, 107b; 107c) on the measurement target; reference beam irradiating means (63; 104) for irradiating a reference beam mirror (66; 108) with at least two of the at least four split beams that are not the object light beams (107a, 107b; 107c), as reference beams (R41, R42; R43); and optical spectrum data generating means (68; 109) for acquiring depth-direction structural data about the measurement target from interference light (R51, R52, R61, R62; R53, R63) to be acquired by causing each of the reference beams (R41, R42; R43) reflected by the reference beam mirror (66; 108) to interfere with a corresponding one of the object light beams (R31, R32; R33) reflected or scattered by the measurement target, characterized in that the object light beam irradiating means (64; 106) includes a front lens system being set in such a way that the object light beams (107a, 107b; 107c) are collimated and cross at one point, an optical beam scanner being placed at a position in which the object light beams (107a, 107b; 107c) cross, and a rear lens system (203, 204) that causes the object light beams (107a, 107b; 107c) passing through the light beam scanner to be condensed on the measurement target, and changes, on the measurement (107a, 107b; 107c) target, a position of each of object light beams (107a, 107b; 107c) with which different positions of the measurement target are irradiated, and a front lens system being set in such a way that the object light beams (107a, 107b; 107c) are collimated and cross at one point, an optical beam scanner being placed at a position in which the object light beams (107a, 107b; 107c) cross, and a rear lens system (203, 204) that causes the object light beams (107a, 107b; 107c) passing through the light beam scanner to be condensed on the measurement target, and changes, on the measurement (107a, 107b; 107c) target, a position of each of object light beams (107a, 107b; 107c) with which different positions of the measurement target are irradiated, and wherein the optical coherence tomography device further comprises a mechanism for causing a lens of the rear lens system (203, 204) for the object light beam irradiating means (64; 106) to move in a direction parallel to a depth direction of the measurement target.