A vehicle air-conditioner provided with an inside air-conditioning unit introducing at least one of inside air and outside air, adjusting the state of the introduced air, and blowing it out into the vehicle compartment, where an air-conditioning electronic control device judges if window glass is liable to fog up based on a window glass surface relative humidity near the window glass in the compartment (degree of ease of fogging). When it is judged that the window glass is liable to fog up, the inside air-conditioning unit is controlled to prevent the window glass from fogging up in defrost control, while when it is judged that the window glass is resistant to fogging, the inside air-conditioning unit is controlled to introduce at least inside air into the compartment.