An eco-humidifier for a vehicle performs a humidifying function by using solar light energy without separate power, and includes: a case having space to accommodate water and in which a light collecting device is installed on a top of the case so as to concentrate solar light; multiple metallic nano particles that sink in the water accommodated in the case to absorb the solar light passing through the light collecting device; and a condenser, an evaporator, and a blower motor connected with one upper side of the case via a connection pipe, where the metallic nano particles are heated by a surface Plasmon resonance phenomenon to vaporize the water to vapor.