This research had aimed to produce a Science Learning Material based on Motivational Strategic of ARCS that is feasible to fascilitate students’critical thinking skill. The learning instrument is developed by using 4-D model with a try out-design namely one group pre-test - post-test design. In order to measure aplicability of the lesson plan, learning obstacles, the result of students’ learning in from of critical thinking  students’ responses to the developed lesson plan. The data collection apply data validation, observation, achievement test, questionaries and documentation. The research data were analysed descriptively both qualitative and quantitative. The research findings were as follows: the validity, the practicality, and the implementation of the learning material. The result of the lesson plans that is categorized as ‘good’, the constraints occurred during the implementation of the learning process. The effectiveness of the learning instrument that was reviewed through: (a) the students’ critical thinking ability measured by n-gain moderate level of category; (b) students’ highly excellent response towards the instrument and the learning process. Based on the data analysis, it can be concluded that the Natural Science Learning Instrument with motivational strategic of ARCS was feasible to fascilitate students’ critical thinking skill.