  The gradient flow is the evolution of fields and physical quantities along a
dimensionful parameter~$t$, the flow time. We give a simple argument that
relates this gradient flow and the Wilsonian renormalization group (RG) flow.
We then illustrate the Wilsonian RG flow on the basis of the gradient flow in
two examples that possess an infrared fixed point, the 4D many-flavor gauge
theory and the 3D $O(N)$ linear sigma model.
