The seven-bedroom, traditional-style home is in Brentwood and not far from where Ricki Lake and Tobey Maguire live, the report said.
Among the property's amenities are a wine cellar, library, pool, three-car garage and a deck with a built-in barbecue, the entertainment news Web site said.
Garner reportedly is five months pregnant. She and her husband -- and fellow film star -- Affleck are already the parents of a 2-year-old daughter named Violet.
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