In this paper, we propose a new method for detecting hemorrhage areas and surgical instruments in robot-assisted laparoscopic surgery images. The proposed scheme utilizes CIELAB information to identify a region of interest (ROI) and segment it. Histogram equalization and Otsu's method are also adopted to compute the detection threshold. Detection is performed automatically and additional adjustment of parameters is not needed. Experiments to verify the proposed algorithm were conducted using actual robot-assisted laparoscopic surgery images. Using the proposed algorithm, the average time consumption was 0.37 s per frame for hemorrhage identification and 0.11 s for instrument detection. The sensitivities were also high enough for practical application.