The experimental study was intended to prove the effects of group investigation (GI) model towards the natural science learning outcome of the elementary school students. The sample which was two classes was taken by using simple random sampling. The data was collected by using treated instruments (syllabus and lesson plans) and the instruments of measuring the learning outcome (pre-test and post-test). The data was analyzed by using prerequisite test analysis and hypothesis test through t-test. The results of the study suggested that GI had significant effect on the learning outcome. The probability value < 0,05 (0,000 < 0,05) and the values of T > Ttable (12,800 >1,991) which meant that Ho was rejected so the GI teaching and learning model had positive effect on the natural science learning outcome.