This aim of the research was to train socioscientific decision making skills for the science students. Students are involved to solve the socioscientific problems by making informative and systematic decisions. The development of socioscientific decision making skills was done by applying biotechnological module based on Problem-based Learning with socioscientific cases. Quasi-experimental design was used in this research. Two science classes were employed in this research: first class for experimental class which had the treatment by applying biotechnology module based on problem-based learning and another class for control class using biology books from school. Those two classes were given the same questions in pre-test and post-test to measure socioscientific decision making skills. The research results showed that the average post-test score of socioscientific decision making skills in experimental class was 82.80 which is higher than the control class (62.32); moreover, normalized gain score in experimental class obtaining 0.745 and this is also higher than that in control class (0.434). The results of ANCOVA analysis show, that there was significant differences in the score of socioscientific decision making skills between experimental class and the control one by the value of F count (25.54), this value was higher than F table (4.075). In addition, the score of partial eta squared was 0,384, which means that the application of PBL-based module with socioscientific cases have the high level of effectiveness to improve socioscientific decision making skills. The result of assessment transcript in the decision making quality showed that experimental class has the decision supported by the justified arguments which is contains 2-4 socioscientific aspects.