Abstrak Penelitian ini bertujuan untuk mengembangkan ensiklopedia alat optik berbasis problem based learning. Jenis penelitian yang digunakan adalah penelitian pengembangan (R&D) dengan model pengembangan ADDIE (Analysis, Design, Development, Implement, Evaluation). Penelitian dilakukan di Laboratorium fisika FMIPA UNJ. Ensiklopedia yang dikembangkan ini dilengkapi dengan model pembelajaran yang sesuai dengan karakteristik materi alat optik. Ensiklopedia telah divalidasi oleh ahli, yaitu ahli materi, ahli media, dan ahli pembelajaran dengan instrumen validasi. Ensiklopedia alat optik terdiri dari 6 materi, yaitu (1) kacamata; (2) kamera; (3) Lup; (4) mikroskop; (5) periskop; dan (6) teleskop. Tahapan problem based learning dalam ensiklopedia ini terdiri dari problem orientation, organize student to learn, investigation, problem solution result, analysis and problem solution evaluation. Ensiklopedia ini dapat digunakan sebagai sumber belajar bagi peserta didik. Kata-kata kunci: Ensiklopedia, Alat Optik, Problem Based Learning, Sumber Belajar Abstract The aim of this study to develop optical instruments encyclopedia based on problem-based learning approach. The research method used is research and development (R & D) with the ADDIE models (Analysis, Design, Development, Implement, Evaluation). The development of optical instruments encyclopedia is done in State University of Jakarta ’s physics laboratory. This encyclopedia has been validated by experts, that is content experts, media experts, and learning experts by providing a validation instrument. Optical instruments encyclopedia consist of 6 titles, that is (1) eyeglasses; (2) camera; (3) magnifying glass; (4) microscope; (5) periscope; and (6) telescope. It is structured by problem-based learning approach stage that is problem orientation, organize student to learn, investigation, problem solution result, analysis, and problem solution evaluation. Overall, this encyclopedia deserves to be used as a learning resource for students. Keywords: Encyclopedia, Optical Instrument, Problem Based Learning, Learning Resource