The purpose of this study was to determine the effect of ice breaking by doing stand-up comedy on the result of mathematical belief. This research was conducted at SMPN 37 Jakarta on 2nd grade in the 2nd-semester academic year 2016-2017. The research design used was the treatment by level 2x2 with learning method as a dependent variable which is the ability to understand the mathematics concept as a moderator variable and mathematical belief as an independent variable. The sampling technique used cluster random sampling. The result showed that the learning through icebreaking by doing stand-up comedy is able to increase the mathematics’ belief of students. In addition, the learning method has the effect of mathematics’ belief which depends on the ability to understand the mathematics concept of the student. Scholars who study by ice breaking with stand-up comedy teaching have the mathematics’ belief higher than scholars who study by the conventional method.