Electric heater apparatus for electric vehicle and method of controlling the same

The present invention relates to an electric heater apparatus including a switch control part for controlling a switching part (13) according to a control command of an air-conditioner controlling part (11); the switching part (13) switched according to a switching control signal of the switch control part for supplying electric power of the power supply part from a heating part; and the heating part for receiving the electric power of the switching part (13) and generating heat, wherein the switching part (13) includes a plurality of switching modules (13a, 13b, 13c) set to control an output load of the heating part, and the switch control part operates one or more switching modules (13a, 13b, 13c) in serial order according to a target heating temperature.