Westside Estate Agency

Jennifer Aniston, 42, sold her Beverly Hills estate for $38 million a few weeks ago, putting her in the clear to buy a new home.

But Jen's not solo in her search ... X17online can exclusively report that she is taking boyfriend Justin Theroux, 39, house hunting with her!

Since Monday, the two have been visiting five to six mansions daily, including Ellen DeGeneres' Beverly Hills home with wife Portia de Rossi (above), which has been on the market since June for a reported $60 million!

Aniston's Beverly Hills home was originally priced at $42 million -- it was purchased for a reported $38 million by financier Bill Gross.

The Horrible Bosses actress is currently still living in that home, but is, our sources tell us, in a "rush to buy." She might have to be out of that house by the end of the month.

Or, maybe she and Justin are just in a hurry to take things to the next level ...

See our gallery below for photos of Ellen's $60 million home, and get more details on Jen's real estate dealings after the jump!