The students' interest can be influenced by the learning model chosen by teachers. Theselection of appropriate learning models can help to increase the interest in learning thateventually affects the motivation of learning. The purpose of this study is to identify theimplementation of problem-based learning model against the motivation to learn Biology in theclass VII ofmaterial environmental pollution. This type ofresearch is a classroom action research.This research was conducted through two cycles of the students in the class VII on Islamic JuniorHigh School Tambakboyo Tuban Academic Year 2013/2014 of 33 students. The results of thisstudy show that the average results ofstudents' learning motivation questionnaire on the first cycleof 72.12% with the criteria motivated enough and rising to the second cycle of 86.24% with thehighly motivated criteria. The conclusion is the application of problem-based learning model canimprove students' motivation of Islamic junior class VII 4-5 Tambakboyo of materialenvironmental pollution.