  In modified gravity, the one-loop matter power spectrum exhibits an
ultraviolet divergence as shown in the framework of the degenerate higher-order
scalar-tensor theory. To address this problem, we extend the effective field
theory of large scale structure to modified gravity theories. We find that new
counterterms appear and renormalize the ultraviolet divergence as a natural
consequence of non-linearity in the modified Poisson equation. The renormalized
one-loop matter power spectrum is useful to test modified gravity theories by
comparing to observations.
