In an optical imaging apparatus for diagnosis, there is generated a closed curve which precisely reproduces the shape of the indwelled stent and the shape of the inner wall of the biological tissue at the indwelling position of the stent. An optical imaging apparatus for diagnosis relating to the present invention is characterized by including: an analysis means for analyzing intensity change in transmission direction of the light from the transmission and reception unit for every one of the respective line data； a detection means, based on the analysis result, for detecting pixel data expressing stent position in the transmission direction； a labeling means for labeling each pixel data expressing the detected stent position； an elimination means for eliminating, within the respective labeling groups applied with the same labels by the labeling means, labeling groups in each of which the number of pixel data in the circumferential direction is a predetermined value or less； a calculation means for calculating center position with regard to each labeling group which was not eliminated； and a generation means for generating a stent closed-curve by using the center position of the each labeling group, which was calculated.
