To reduce time and labor for correction by improving the accuracy of heat flux measurement.

A heat flux meter 1 is formed by including: a heat receiving portion 2 equipped with a temperature sensor 3 on a surface of a heat receiving plate 8; a heat transmission rod member 4 attached to a back surface of the heat receiving plate 8 at one end portion in a longitudinal direction; a cooling jacket 5 attached to the heat transmission rod member 4 so as to slide in the longitudinal direction; and a ball screw direct-acting mechanism 6 for changing a position of the cooling jacket 5. When the heat flux measurement of a measuring object 7 is executed by the heat flux meter 1, if a heat gain from the measuring object 7 is large to the heat receiving portion 2, the position of the cooling jacket 5 in the longitudinal direction of the heat transmission rod member 4 is brought close to the heat receiving portion 2, and if the heat gain is small, the position of the cooling jacket 5 is separated from the heat receiving portion 2. Therefore, heat resistance generated when the heat receiving portion 2 is cooled by the cooling jacket 5 through the heat transmission rod member 4 is properly changed, thereby reducing difference between the surface temperature of the heat receiving portion 2 and the temperature of the measuring object 7.