A cooling apparatus comprising: a case in which a refrigerant passage through which a refrigerant flows is formed; and an element module partially disposed within said refrigerant passage and including an element provided inside, a portion of said element module in contact with said refrigerant being formed of an insulating material, said element including a first unit element and a second unit element that generates an amount of heat greater than that generated by said first unit element, wherein said element module comprises a first insulating substrate in contact with said refrigerant, a second insulating substrate facing said first insulating substrate and disposed at a distance from said first insulating substrate, and being in contact with said refrigerant, and said first insulating substrate including a first inner surface facing said second insulating substrate, and a first outer surface positioned opposite to said second insulating substrate with respect to said first inner surface, said second insulating substrate including a second inner surface facing said first insulating substrate, and a second outer surface positioned opposite to said first insulating substrate with respect to said second inner surface, characterized by said first unit element being provided in a position closer to said first inner surface than said second inner surface, and said second unit element being provided in a position closer to said second inner surface than said first inner surface, wherein the flow path widths (W 1, W 2) between said first and second insulating substrates (50, 51) and the inner walls of said refrigerant passage are such that a flow velocity of refrigerant flowing between the second outer surface of the second insulating substrate and an inner wall surface of said refrigerant passage is higher than that of refrigerant flowing between the first outer surface of the first insulating substrate and the inner wall surface of said refrigerant passage. a case in which a refrigerant passage through which a refrigerant flows is formed; and an element module partially disposed within said refrigerant passage and including an element provided inside, a portion of said element module in contact with said refrigerant being formed of an insulating material, said element including a first unit element and a second unit element that generates an amount of heat greater than that generated by said first unit element, wherein said element module comprises a first insulating substrate in contact with said refrigerant, a second insulating substrate facing said first insulating substrate and disposed at a distance from said first insulating substrate, and being in contact with said refrigerant, and said first insulating substrate including a first inner surface facing said second insulating substrate, and a first outer surface positioned opposite to said second insulating substrate with respect to said first inner surface, said second insulating substrate including a second inner surface facing said first insulating substrate, and a second outer surface positioned opposite to said first insulating substrate with respect to said second inner surface, characterized by said first unit element being provided in a position closer to said first inner surface than said second inner surface, and said second unit element being provided in a position closer to said second inner surface than said first inner surface, wherein the flow path widths (W 1, W 2) between said first and second insulating substrates (50, 51) and the inner walls of said refrigerant passage are such that a flow velocity of refrigerant flowing between the second outer surface of the second insulating substrate and an inner wall surface of said refrigerant passage is higher than that of refrigerant flowing between the first outer surface of the first insulating substrate and the inner wall surface of said refrigerant passage.