Robbie Williams' jockstrap a collectable

The Australian auction house selling a jockstrap worn by music star Robbie Williams' says it hopes to net up to $800 for the intimate item.

The jockstrap, signed by Williams, was worn by the singer for the soccer-themed cover of his third studio album Sing When You're Winning.

Auctioneers Leonard Joel estimates it will fetch between $600 and $800 when it goes under the hammer in early June.

Head of Collectables Giles Moon says it's a legitimate piece of rock'n'roll memorabilia, despite the intimate nature of the garment.

"It's certainly not the most unusual thing I've sold," he told AAP.

"I've been involved in the sale of things like stage worn costumes worn by Madonna that are quite risque."

The jockstrap came directly from Williams via a 2001 Sotheby's charity auction, Mr Moon said.

"It certainly has some value to a collector ... based upon the fact it came from that sale initially," Mr Moon said.

He said it shouldn't be viewed as something "unsavoury", but rather, a genuine piece of music history.

Other notable items to be auctioned in the collection include a jacket worn by the Rolling Stones' Keith Richards for the Voodoo Lounge tour and Beatles photographs.

There's even Wolverine's X-Men black leather suit, which is expected to fetch up to $60,000.