In the recent medical fields, multimodal imaging is considered to be important technique for improving diagnostic accuracy. We have developed integrated DOl-PET and MRI system which can simultaneously acquire PET and MRI data. The system consists of 0.3 T permanent magnet open MRI scanner with light-guide based PET insert. The system has axial and transaxial field of view of 80 mm. In order to improve spatial resolution, the PET insert has two layers of crystals and is possible to acquire data with depth-of-interaction (DOl) mode. Iterative reconstruction software was implemented for the image reconstruction of PET. This system can visualize physiological function and anatomical information within short period.