Research has been carried out using the PIMCA learning model introduced by Cosmas Poluakan. The aims of this study is to describe the learning difficulties of the third semester students of Physics Education study program, in understanding the Lorentz force concept through learning using PIMCA learning model based on MR-SR (multiple representations - semiotic source). The research method is a descriptive analysis method, with the procedure beginning with giving a pre-test, then following the 4 stages of PIMCA learning. The results showed that the average of pre-test results was 7% and the average of post-test results was 37%. These results indicate that even though there is an increase in the average of mastery the Lorentz force concept, generally students still have difficulty in writing down the complete vector magnitude, determining the relationship of force, electric current and magnetic field in a three-dimensional coordinate system and also need to be given more time so that students more freely explore the concept of Lorentz force. The results of this study recommend that in order to understand the Lorentz force concept, the use of the PIMCA model needs to be accompanied by giving more practice questions, and doing virtual practicum.