  We reexamined the gravitational time delay of light, allowing for various
models of modified gravity. We clarify the dependence of the time delay (and
induced frequency shift) on modified gravity models and investigate how to
distinguish those models, when light propagates in static spherically symmetric
spacetimes. Thus experiments by radio signal from spacecrafts at very different
distances from Sun and future space-borne laser interferometric detectors could
be a probe of modified gravity in the solar system.
