  We test a pentaquark model of the negative parity hyperon Lambda(1405). We
use the model where valence four quarks and one antiquark move in a potential
relativisticaly and interact with themselves and each other through gluon and
NG boson. We calculate mass shift of the system and find that there are two
Lambda(1405) with almost degenerate mass: one flavor singlet and one flavor
octet. We calclate also sigma-term and scalar form factor of the hyperon and
show their usefulness to deduce the number of valence quark in the hypeon.
