To easily measure the flow of the heat radiated from a heat source to the peripheral space throughout the space with high accuracy and high response even when the flow velocity is high.

A heat flow velocity measuring device is provided with a heating member 1 which has the shape insertable into the space having the change of temperature and the flow, and ignoring the heat flow, a device for energizing the heating member 1 for rising the temperature thereof and a device for cooling the heating member 1, and measures the change of the temperature of the heating member by an infrared ray camera. On this occasion the heating member 1 comprises a spider web-shaped structure where the linear materials are concentrically and radially combined, or the wire mesh structure.