A positron emission tomography (PET) for animals using cadmium telluride (CdTe) detectors was developed for the purpose of biomedical study using rats and mice. The spatial resolution of 0.8mm FWHM within the central 20 mm-diameter of field of view (FOV) was obtained by the use of small CdTe elements of 1.1 mm 1.0 mm 5 mm. The FOV is 64 mm in diameter and 26 mm in axis. Fine images were successively obtained following [18F]fluorodeoxyglucose ([18F]FDG) injection to a rat and a mouse. In the fine [18F]FDG images, the cerebral cortex, the gray matter and the corpus striatum was able to be respectively distinguished.