According to J.-L. Brylinski,
there is a natural almost complex structure J on the space K of all knots in the
Euclidean space R3. The almost complex structure is formally integrable on K, i.e,
the Nijenhuis tensor of J vanishes. The problem is whether J is integrable and hence
K is a complex manifold. In this paper, we study the integrability of J explicitly in
view point of a Frobenius problem.