This study aims to determine whether there was differences effect in improving student's critical thinking skills (1) between students who get Problem-based Learning, Mathematical Problem Posing, and conventional learning, and (2) based on gender differences. This study used a quantitative method with the pre-test-posttest two treatment design. Data were collected using instruments: test, documentation, and observation. Data was taken from 124 undergraduate students from the mathematics education study program at Universitas Negeri Semarang, Indonesia. Data analysis was done by using the normalized gain and the MannWhitney test. The results showed that in improving student's critical thinking skills (1) Problem-based Learning and Mathematical Problem Posing provide better effect than conventional learning, (2) there was no significant difference in effect between Problem-based Learning and Mathematical Problem Posing, and (3) there was no significant difference in effect based on gender differences.