  We derive the off-shell Noether current and potential in the context of
Horndeski theory, which is the most general scalar-tensor theory with a
Lagrangian containing derivatives up to second order while yielding at most to
second-order equations of motion in four dimensions. Then the formulation of
conserved charges is proposed on basis of the off-shell Noether potential and
the surface term got from the variation of the Lagrangian. As an application,
we calculate the conserved charges of black holes in a scalar-tensor theory
with non-minimal coupling between derivatives of the scalar field and the
Einstein tensor.
