This diploma thesis discusses modal analysis of structures using finite element method within the open-source package SfePy. Initially, the theorethical background and general principles of finite element method are given. The work is continued with the instructions on how to use the package SfePy. Through the thesis, the comparison between the open-source package SfePy and the commercial software Abaqus is made. Thesis shows that open-source package SfePy could be powerful at solving modal analysis problems and also comparable to the commercial software.