Provided is an apparatus for generating a single-polarization mode-locked laser capable of energy control. The apparatus for generating a single-polarization mode-locked laser is configured to adjust at least one of a focal length of a lens focusing laser light on a semiconductor saturable absorber mirror (SESAM) functioning as a saturable absorber, power of pump laser light, and reflectivity of an output coupler (OC) to set fluence, which is defined as energy density per unit area of the laser light incident on the saturable absorber, to be greater than reference fluence, which is energy density per unit area of the laser light incident on the saturable absorber when reflectivity of the saturable absorber is a maximum. Accordingly, it is possible to generate a single-polarization mode-locked laser, of which energy can be controlled, without generating multiple pulses.