Primordial Black Hole Formation in Supergravity

We study a double inflation model (a pre-inflation + a new inflation) in supergravity and discuss formation of primordial black holes which may be identified with massive compact halo objects (MACHOs) observed in the halo of our galaxy. The pre-inflation drives an inflaton for the new inflation close to the origin through supergravity effects and the new inflation naturally occurs. If the total e-fold number of the new inflation is smaller than $\sim 60$, both inflations produce cosmologically relevant density fluctuations. If the coherent inflaton oscillation after the pre-inflation continues until the beginning of the new inflation, density fluctuations on small cosmological scales can be set suitably large to produce black holes MACHOs of masses $\sim 1 M_{\odot}$ in a wide region of parameter space in the double inflation model.