An optical coherence tomography device comprising: an OCT optical system configured to obtain an OCT signal generated based on measurement light radiated to a test substance and a reference light; a front observation optical system configured to obtain a front image of the test substance; and a control portion adapted to control the OCT optical system to obtain a plurality of first OCT signals, which are temporally different from each other, with respect to a first region on the test substance and adapted to, after controlling the OCT optical system to obtain the plurality of first OCT signals, to control the OCT optical system to obtain a plurality of second OCT signals, which are temporally different from each other, with respect to a second region on the test substance, the second region being different from the first region; the control portion further adapted to control the front observation optical system to obtain a first front image of the test substance at the time the OCT optical system obtains the plurality of first OCT signals; the control portion further adapted to control the front observation optical system to obtain a second front image of the test substance after the OCT optical system obtains the plurality of first OCT signals; the control portion further adapted to detect a positional deviation between the first front image and the second front image and determining whether or not the plurality of first OCT signals are good based on the result of the detected positional deviation; characterized by the control portion further adapted to obtain motion contrast data of the test substance by processing the plurality of first OCT signals when it is determined that the plurality of first OCT signals are good, and the timing of starting the operation of obtaining the plurality of OCT signals in a predetermined scanning region is not in synchronization with the timing of starting the operation of obtaining the front images, and if the control portion determines that the plurality of first OCT signals are not good, the control portion is further adapted to control the OCT optical system to obtain the plurality of first optical signals with respect to the first region again after the control portion controls the OCT optical system to obtain the plurality of second OCT signals. an OCT optical system configured to obtain an OCT signal generated based on measurement light radiated to a test substance and a reference light; a front observation optical system configured to obtain a front image of the test substance; and a control portion adapted to control the OCT optical system to obtain a plurality of first OCT signals, which are temporally different from each other, with respect to a first region on the test substance and adapted to, after controlling the OCT optical system to obtain the plurality of first OCT signals, to control the OCT optical system to obtain a plurality of second OCT signals, which are temporally different from each other, with respect to a second region on the test substance, the second region being different from the first region; the control portion further adapted to control the front observation optical system to obtain a first front image of the test substance at the time the OCT optical system obtains the plurality of first OCT signals; the control portion further adapted to control the front observation optical system to obtain a second front image of the test substance after the OCT optical system obtains the plurality of first OCT signals; the control portion further adapted to detect a positional deviation between the first front image and the second front image and determining whether or not the plurality of first OCT signals are good based on the result of the detected positional deviation; characterized by the control portion further adapted to obtain motion contrast data of the test substance by processing the plurality of first OCT signals when it is determined that the plurality of first OCT signals are good, and the timing of starting the operation of obtaining the plurality of OCT signals in a predetermined scanning region is not in synchronization with the timing of starting the operation of obtaining the front images, and if the control portion determines that the plurality of first OCT signals are not good, the control portion is further adapted to control the OCT optical system to obtain the plurality of first optical signals with respect to the first region again after the control portion controls the OCT optical system to obtain the plurality of second OCT signals.