In this study, we evaluated mechanical properties of breast cancer stem-like/tumor-initiating cells (CSC/TICs) from MCF7 cell line. By use of local measurement techniques, such as atomic force microscopy, magnetic or optical tweezers, determination of mechanical properties of an individual living cell in liquid conditions, similar to natural environment has become possible. In this study Young's modulus of individual cancer stem cells were measured as an indicator of cell elasticity using atomic force microscopy (AFM) compared to that of cancer cells. Results indicated that the enriched CSC/TICs population (0.357±0.092kPa) were softer than their cancer cells (MCF7 cell line) (1.04±0.27 kPa). Based on the significant difference between mechanical properties of CSC and cancer cells, the progression of cancer cells from cancer stem cells may be characterized.