  A key ingredient in the Taylor-Wiles proof of Fermat last theorem is the
classical Ihara's lemma which is used to rise the modularity property between
some congruent galoisian representations. In their work on Sato-Tate,
Clozel-Harris-Taylor proposed a generalization of the Ihara's lemma in higher
dimension for some similitude groups. The main aim of this paper is then to
prove some new instances of this generalized Ihara's lemma by considering some
particular non pseudo Eisenstein maximal ideals of unramified Hecke algebras.
As a consequence, we prove a level rising statement.
