The Minardi PS04B was a Formula One race car used by Minardi Cosworth in the 2004 Formula One season.

In 2003 all of the Arrows A23 chassis and the full Arrows Grand Prix International intellectual property rights were bought by Minardi. The Arrows A23 was renamed the Minardi PS04A[2] and in back-to-back tests it was found superior to the Minardi's PS03. Minardi however decide that they could not run a "pure-Arrows" and hence used the Arrows intellectual property, which included the new designs for the Arrows A24[3] and the best elements from the PS03 and PS04A / Arrows A23 to develop the Minardi PS04B for the 2004 season.[4][5]

Period reports even hinted that the PS04B was possibly based more closely on the Arrows A24 than Minardi might have been prepared to publicly admit.[3][6]

For following season the PS04B was developed into the PS05.

The PS04B was driven by rookie Gianmaria Bruni, and Zsolt Baumgartner who had moved from Jordan. The team managed to earn their first point in two years, after Baumgartner finished 8th (albeit last) at the United States Grand Prix.

In 2005, Minardi used a PS04B chassis for the first three races of the season before they made a new PS05 chassis due to assembly problems.