Heat flux meter and anomaly diagnosis device

A heat flux meter 2 is provided with a heat flux sensor 10 and a heat dissipation unit 20. The heat flux sensor 10 has one face and another face on the opposite side. The heat flux sensor 10 outputs a sensor signal corresponding to the temperature difference between the one face side and the other face side. The heat dissipation unit 20 dissipates, to an exterior space, heat from a heat generation source 202 of a target object 200. The heat flux sensor 10 is disposed in a heat conduction path between the heat generation source 202 and the heat dissipation unit 20. The one face side of the heat flux sensor 10 is disposed on the heat generation source 202 side in the heat conduction path. The other face side of the heat flux sensor 10 is disposed on the heat dissipation unit 20 side in the heat conduction path.