This is some serious coin.

A California man cleaning out the home of his late father-in-law discovered a secret stash one million pennies.

Real estate agent John Reyes found the copious collection of copper coins — with a face value of $10,000 — in a basement crawlspace under the Los Angeles abode, KTLA reported.

The first clue to the treasure came as he and family members assisting in the cleanup found some loose pennies in disintegrated paper rolls.

Next, they located crates, boxes and dozens of bank bags filled with the coins.

They determined that they are copper, not zinc, which the United States switched to in the early 1980s.

At first, the family intended to just trade them in for more usable cash, but then realized that didn’t make cents.

“We’ve got to take these to Coinstar,'” Reyes, who lives in Ontario, Calif., told the outlet of his initial thoughts. “We didn’t want to pay 8%, and there’s no way we can take these all the way [home] to Ontario.”

Local banks refused to take them off their hands.

“I don’t even have the room in my vault,” Reyes recalled one bank manager saying. “Don’t bring them here.”

So Reyes transported the pile to his Ontario home, over 35 miles from L.A. — which was no easy feat.

“Literally bag-by-bag, we had to take them out of the basement, up the stairs, and into the trucks … it took hours,” Reyes explained. “It took a whole day just to get them out of the crawlspace.”

Banks closer to his home didn’t want them either — and suggested they go through the collection to see if any are worth more than a penny.

Reyes’ father-in-law Fritz, a well-known longtime butcher in Hollywood, had the habit of purchasing copper pennies, knowing their value would increase over time.

However, the clan is not interested in spending more time on the project, so Reyes listed the coins on OfferUp, a resale website, asking for $25,000.

Although that’s more than double their worth in currency, “the value is in the uniqueness,” he said.