  We derive entropic uncertainty relations for successive generalized
measurements by using general descriptions of quantum measurement within two
{distinctive operational} scenarios. In the first scenario, by merging {two
successive measurements} into one we consider successive measurement scheme as
a method to perform an overall {composite} measurement. In the second scenario,
on the other hand, we consider it as a method to measure a pair of jointly
measurable observables by marginalizing over the distribution obtained in this
scheme. In the course of this work, we identify that limits on one's ability to
measure with low uncertainty via this scheme come from intrinsic unsharpness of
observables obtained in each scenario. In particular, for the L\"{u}ders
instrument, disturbance caused by the first measurement to the second one gives
rise to the unsharpness at least as much as incompatibility of the observables
composing successive measurement.
