An optical coherent tomographic image forming apparatus comprising: a light source; an optical divider configured to divide a light outputted from the light source into a measurement light and a reference light; an optical probe unit which is insertable into inside of a body lumen, comprises a catheter sheath and an imaging core arranged in the catheter sheath, the imaging core comprises an optical fiber and an optical deflection unit provided at a distal end of the optical fiber, the optical probe unit configured to emanate the measurement light to the biological tissue and receive a reflected light; a drive unit configured to rotate the imaging core inside the catheter sheath around the axial direction of the optical probe unit and to move it along the axial direction of the optical probe unit, a signal processing unit configured to generate a cross-sectional image inside a biological tissue based on the light intensity of an interference light which is obtained from the reflected light and the reference light; characterized in that the drive unit comprises: a first switch for instructing rotation of the optical deflection unit at a first speed; a second switch for instructing rotation of the optical deflection unit at a second speed which is higher than the first speed; and a driving controller (204, 224) configured to drive the optical deflection unit rotationally at the first speed in case of detecting instruction operation of the first switch and change the rotation speed of the optical deflection unit to the second speed, in case of detecting instruction operation of the second switch, under the condition that the optical deflection unit rotates at the first speed when the second switch is instructionally operated. a light source; an optical divider configured to divide a light outputted from the light source into a measurement light and a reference light; an optical probe unit which is insertable into inside of a body lumen, comprises a catheter sheath and an imaging core arranged in the catheter sheath, the imaging core comprises an optical fiber and an optical deflection unit provided at a distal end of the optical fiber, the optical probe unit configured to emanate the measurement light to the biological tissue and receive a reflected light; a drive unit configured to rotate the imaging core inside the catheter sheath around the axial direction of the optical probe unit and to move it along the axial direction of the optical probe unit, a signal processing unit configured to generate a cross-sectional image inside a biological tissue based on the light intensity of an interference light which is obtained from the reflected light and the reference light; characterized in that the drive unit comprises: a first switch for instructing rotation of the optical deflection unit at a first speed; a second switch for instructing rotation of the optical deflection unit at a second speed which is higher than the first speed; and a driving controller (204, 224) configured to drive the optical deflection unit rotationally at the first speed in case of detecting instruction operation of the first switch and change the rotation speed of the optical deflection unit to the second speed, in case of detecting instruction operation of the second switch, under the condition that the optical deflection unit rotates at the first speed when the second switch is instructionally operated. a first switch for instructing rotation of the optical deflection unit at a first speed; a second switch for instructing rotation of the optical deflection unit at a second speed which is higher than the first speed; and a driving controller (204, 224) configured to drive the optical deflection unit rotationally at the first speed in case of detecting instruction operation of the first switch and change the rotation speed of the optical deflection unit to the second speed, in case of detecting instruction operation of the second switch, under the condition that the optical deflection unit rotates at the first speed when the second switch is instructionally operated.