As a herbicide-free weeding method, our research group are developing an autonomous running paddy weeding robot that can travel by a simple operation. The paddy weeding robot removes the weeds by churning up the soil and inhibits the growth of the weeds by blocking-off sunlight. Before now, the paddy weeding robot has detected rice seedlings with capacitive touch sensors and turned to next rice seedlings row. However, the detection accuracy to move next rice seedlings row wasn’t sufficient. In this paper, we propose a detecting system which can detect rice seedlings from images taken by a camera sensor using You Only Lock Once (YOLO). From the experimental results, we confirmed that a detection system that sorted rice seedlings by growth obtained high values in the precision and recall rates, which are evaluation indices.