A method of generating a terahertz wave and apparatuses performing the method are disclosed. According to an example embodiment, a method of generating a terahertz wave includes outputting a laser comb by modulating a laser output from a laser source based on a linearly modulated frequency of an output that is output from a frequency source, and generating a terahertz wave based on a first comb line and a second comb line selected from the laser comb.