The purpose of this research is to develop and implement mathemathic problem solving instruction in order to increase students critical thinking. The subject of this research are 192 first graders of four junior high school inb malang Indonesia. 96 students are from school category I and the rest students are from school category II. School cactegory I has students who have achieved high score in elementary school national examinition while the school category II has students mathematics problem solving instruction can increase student critical thinking in both schools (category I and II). The students are more active in the teaching and learning processes. Moreover they are more critics and careful when handle mathematics problem.