Mathematical communication skills convey and interpret mathematical ideas through drawings, tables, diagrams, formulas, or demonstrations. The inquiry-based learning model allows students to discover data, facts, and information from various sources to provide experiences. This study aims to analyze students’ mathematical communication skills, improve them using the inquiry-based learning model, and then deepen them through a description. This study uses an explanatory sequential method combining quantitative and qualitative research. The research subjects were 23 VIB students in the control class and 23 VIA students in the experimental class. The study results show that students’ mathematical communication skills are divided into weak, moderate, and strong skills. The independent sample t-test results showed a significant influence of applying the inquiry-based learning model with a sig. 0.003 (p <0.05). Strong and moderate mathematical communication skills showed an increase of 47.83% and 13.04%, while weak skill levels showed a decrease of 60.87%. The improvement of mathematical communication skills is presented as a description of observation and interview results. The research conclusion reveals that applying the inquiry-based learning model can improve students’ mathematical communication skills in solving problems of circumference and area of circles in elementary school students.