  We study the space of nearly K\"{a}hler structures on compact 6-dimensional
manifolds. In particular, we prove that the space of infinitesimal deformations
of a strictly nearly K\"{a}hler structure (with scalar curvature scal) modulo
the group of diffeomorphisms, is isomorphic to the space of primitive co-closed
(1,1)-eigenforms of the Laplace operator for the eigenvalue 2scal/5.
