The aim of this study is to examine the number sense skills of preservice elementary school mathematics teachers. This study was conducted by using the survey model among descriptive research methods. A total of 111 preservice teachers studying at second and third grades in the elementary school mathematics teaching program at a state university participated in the study. The data of the study were collected by using the number sense test consisting of 17 questions and developed by Kayhan-Altay (2010). The findings of the study indicated that the number sense performances of preservice elementary mathematics teachers were lower than expected and there was a significant difference in favour of third-grade students. It is considered that the "Special Training Methods I and II" courses and the "Mathematics Curriculum" course, which are taught in third grades and in which subjects such as estimation and making mental calculations, etc. superficially related to number sense are mentioned, may cause this difference. Thus, it was suggested that it was necessary to include courses consisting of number sense and how it can be developed in the curriculum.