In this paper, we propose a new algorithm to detect the irises of both eyes from a human face in an intensity image. Using the separability filter proposed by Fukui et al., the algorithm first extracts intensity valleys, which we call blobs in this paper, as the candidates for the irises. Next, for each pair of blobs, the algorithm computes a cost using Hough transform and separability filter to measure the fit of the pair of blobs to the image. Then, the algorithm selects a pair of blobs with the smallest cost as the irises of both eyes. As the result of the experiment using all faces without spectacles in the face database of the University of Bern, the success rate of the proposed algorithm was 96.5[%] on the average.