We consider the decay of solution to fractional diffusion equation with the distributed order Caputo derivative. We assume that the elliptic operator is timedependent and that the weight function, contained in the definition of the distributed order Caputo derivative, is just integrable. We establish the relation between behavior of weight function near zero and the decay rate of solution.Keywords: distributed order fractional diffusion, weak solutions, time-depended elliptic operator, temporal decay of solution.