Prosecutors have accused Melbourne-born Robert Andrew Fiddes Ellis of molesting 24 children since 2014.
The 69-year-old allegedly lured children to his house by offering them gifts and money, before touching them inappropriately while bathing them.
Bali police arrested Ellis in January after a tip-off from a local child protection agency about a suspicious foreigner who frequently invited young children to his home.
Ellis could face 15 years in prison if found guilty.
His lawyer, Soti Sapurah, denied Ellis had molested the children, claiming his client only bathed them and never forced them to engage in inappropriate acts.
"Robert did not intend to molest the children, he only wanted to make them happy," Sapurah told AFP outside Denpasar District Court.
Ellis will return to court in July.
Bali is a popular holiday destination for global tourists, particularly Australians, who flock to the island for its surf, resorts and night life.
But some have wound up in prison on child sex offences. In 2009, 61-year-old Australian Philippe Robert Grandfield was sentenced to eight years prison for paying underage boys for sexual favours.
- AFP