Structures used in the application must perform their duties undamaged during the time they are used. Cracks often affect the dynamic properties of the structural elements and can cause severe durability problems. The crack detection in the structural elements and vibration analysis are vital in engineering applications and so far has been the subject of many researches. In present study, free vibration analysis of the un-cracked and cracked cantilever beam was performed and the first three natural frequencies were determined as theoretically and numerically. After verifying the results, the beams were modeled using CATIA software and analyzed using the finite element method with ANSYS software in order to get quick results. The effect of the location of the crack, the depth of the crack, the width of the crack and the number of cracks on the first three natural frequencies was investigated by performing a parametric study. The results are given in tables and graphs.