In this paper, a hybrid observer for interleaved boost converter is proposed. This converter is amid of new structures which based on parallaling converters, characterized by a strong currents with high switching frequencies. After recalling the dynamical equations of the converter, its hybrid dynamical behaviour and advantages are illustrated. This linear switched system has unobservable configuration modes linked to particular switching sequences. By using a new concept called the Z(Tn)-observability this problem was solved. The proposed observer is based on the homogeneous observer alghorithm coupled with an estimator. The performances of the designed observer are highlighted by simulation studies in MATLAB/Simulink, a finite time convergence is obtained even in the presence of input variation.