In this study, it is aimed for following two points. The first point is to devise the instruction method for "the ability to judge whether a conclusion is demonstrated scientifically or not?" in a scientific thinking. The second point is to investigate the effect of the instruction method. This ability is "an ability to judge the scientific problem solving that others did". Therefore, the instruction method that we devised aimed at letting a learner acquire a viewpoint and stratagem to judge whether "the scientific problem solving that others did" was appropriate. And, for the children of 154 elementary school sixth grade, a unit practiced "a mechanism of the combustion". As a result, the instruction method was effective in upbringing of this ability.