The chief executive of the royal commission into child sexual abuse, Janette Dines, has resigned.

Dines will leave her position on 6 June.

Justice Peter McClellan, who chairs the royal commission, said Dines had been the driving force behind establishing the commission since its inception in late 2012, but gave no reason for her departure.

"Ms Dines has successfully created the structure and facilities that have enabled the royal commission to achieve a large amount in a short time," McClellan said in a statement.

"On behalf of the commissioners, I express our great appreciation to Ms Dines for the contribution she has made to our work."

Dines said she felt privileged to be involved with the commission and was happy to leave it in "good shape", but also offered no reason for her resignation.

Next month the commission will hear from 50 child sex abuse victims in private sessions in Melbourne.

Before announcing her resignation, Dines said private sessions were an important way for commissioners to find out first-hand about the impact of child sexual abuse and better understand how it could be prevented.

"The information that Victorians are sharing with the royal commission will help to inform recommendations on how to improve laws, policies and practices in Australia in order to provide a safer future for children," she said in a statement on Monday.

The commission will deliver its interim report to the governor-general on 30 June.