  We make a detailed analysis on validity of gauge-fixing conditions and the
structure of propagators in the Wess-Zumino-Witten-type open superstring field
theory. First, we generalize the gauge-fixing conditions considered in JHEP 03
(2012) 030 [arXiv:1201.1761] by the present author et al., and propose a large
class of conditions characterized by zero modes of world-sheet oscillators.
Then we demonstrate its validity: we prove that gauge degrees of freedom allow
us to impose the conditions, and that the conditions fix the gauges completely.
Moreover, we elucidate how the information about the gauge choices is reflected
in the structure of propagators. The results can be readily extended to the
case in which gauge-fixing conditions involve linear combinations of the
world-sheet oscillators, including nonzero modes. We investigate also such
extended gauges, which are the counterpart of linear $b$-gauges in bosonic
string field theory, and obtain the corresponding propagators.
