A man secretly filmed more than 200 people, including a girl and boy, in Sydney public toilets for his own "sexual gratification," a court has been told.

Benjamin Moorhouse allegedly placed secret cameras under the sink of toilets at Parramatta and North Sydney train stations, and at a disabled toilet at Westfield Parramatta shopping centre, in February and March.

The 40-year-old, who was arrested on March 22, appeared at Parramatta Local Court on Wednesday, where his lawyer indicated he would plead guilty to all charges.

Moorhouse is charged with five counts of filming a person in a private act for the purpose of "sexual arousal or sexual gratification".