An elementary school janitor in Suffolk County was arrested Friday for passing love notes to a 7-year-old student, police said.

The suspect, an 18-year-old whose name was not released, spoke to the girl at John S. Hobart Elementary in Shirley and asked her if she had internet access or other means to chat online, cops said.

He then passed her his cellphone number and asked her to get in touch with him, authorities said.

Investigators found the suspected perv had left the girl love notes in her desk before he talked to her, police said.

He was arrested Friday and slapped with an endangering the welfare of a child, cops said. He’s expected to be arraigned on Saturday.