  The Picard number of a Fano manifold X obtained by blowing up a curve in a
smooth projective variety is known to be at most 5, in any dimension greater
than or equal to 4. We show that the Picard number attains to the maximal if
and only if X is the blow-up of the projective space whose center consists of
two points, the strict transform of the line joining them and a linear subspace
or a quadric of codimension 2. This result is obtained as a consequence of a
classification of special types of Fano manifolds.
