Billionaire investor Warren Buffett told CNBC he can't see any reason for investors to buy 30-year bonds right now.

"It absolutely baffles me who buys a 30-year bond, the chairman and CEO of Berkshire Hathaway said on "Squawk Box" on Monday. "I just don't understand it."

"The idea of committing your money at roughly 3 percent for 30 years ... doesn't make any sense to me," he added.

Buffett said he wants his money in companies, not Treasurys — making the case throughout CNBC's three-hour interview that he sees stocks outperforming fixed income.