The inactivation of viruses such as M13 bateriophages subject to excitations by a very low power visible femtosecond laser has been studied. Our experimental results show that for a visible femtosecond laser having λ = 425nm and a pulse width of 100 fs, the M13 bacteriophages are inactivated when the laser power density is greater than or equal to 50 MW / cm2. The functionality of M13 bacteriophages has been shown to be critically dependent on the pulse width as well as power density of the excitation laser. Our work demonstrates that by using a very low power visible femtosecond laser, it is plausible to inactivate viruses such as the M13 bacteriophages through Impulsive Stimulated Raman Scattering (ISRS) process. These experimental findings lay down the foundation for a novel new avenue of selectively inactivating microorganisms while leaving the sensitive materials unharmed by manipulating and controlling with femtosecond laser systems.