  The no-ghost theorem for Neveu-Schwarz string is directly proved in
0-picture. The one-to-one correspondence between physical states in 0-picture
and those in the conventional (-1)-picture are confirmed. It is shown that a
non-trivial metric consistent with the BRST cohomology is needed to define a
positive semi-definite norm in the physical Hilbert space. As a by-product, we
find a new inverse picture changing operator, which is non-covariant but has
non-singular operator product with itself. A possibility to construct a new
gauge invariant superstring field theory is discussed.
