Parents say advertising for an upcoming horror film should be banned from roadside billboards because the image is scaring their children.

IT Chapter Two is the sequel to the highest grossing horror film of all time and will air in Australian cinemas from Thursday.

Advertising for the MA15+ film is being plastered in busy thoroughfares before it hits the big screen.

Parents say this poster is scaring their kids. (9News)

"It just totally freaks them out," Brisbane mother Kellie told 9news.

Her daughter Piper said the posters, which feature iconic evil clown Pennywise, have given her nightmares.

"I get really scared because it's hard to go to bed when you have a scary picture in your mind," she said.

"Before I go to bed, I have to check the whole room.

"And when I finally go to bed I will wake up after a nightmare."

Jane Swan said her child is "terrified" by the poster.

"Some people do enjoy going to horror movies and that's fine and that's their choice, and I understand that but we're not choosing to see this poster."

IT Chapter Two is the sequel to the highest grossing horror film of all time. (9News)

Ms Swan said she issued a complaint, believing advertising for movies with the MA15+ rating should be restricted in areas frequented by children.

She was told "Ad Standards generally has no jurisdiction over the placement or timing of advertisements, except when considering the use of language or sex, sexuality or nudity in advertising".