Ultra superfine imaging unit and videoscope

An ultra superfine imaging unit applicable to an insertion tip portion of a videoscope, the insertion tip portion having an external size settable to an ultra small size of several millimeters or less, the ultra superfine imaging unit comprising:

• a case main body having a shape of a hollow cylinder and arrangeable in the insertion tip portion;
• at least one light emitting portion accommodated in the case main body and configured to output light to an observation object;
• and
• a light receiving portion accommodated in the case main body and configured to receive input of an image from the observation object illuminated with light, wherein
• the light emitting portion is arranged along a circumference of the light receiving portion inside the case main body, further comprising
• a holder having a shape of a hollow square prism and configured to hold the light emitting portion and the light receiving portion inside the case main body, wherein
• the holder comprises four wall portions opposed to each other in parallel in such a manner as to divide an inside of the case main body, and adjacent wall portions of the four wall portions are orthogonal to each other,
• the inside of the case main body is divided into a first region and a second region arranged along a circumference of the first region in a state where the holder is accommodated in the case main body,
• the first region has a square cross-sectional contour surrounded by the four wall portions,
• the second region has a cross-sectional contour surrounded by the walls and the case main body,
• the light receiving portion is accommodated in the first region, and
• the light emitting portion is accommodated in the second region.