The tram's back wagon was derailed and hit a passing tram. Another derailment injured 12 passengers.
The unnamed teenager was questioned by police and confessed to switching the tram tracks three times. The device he created to control the points was found at his home.
"He studied the trams and the tracks for a long time and then built a device that looked like a TV remote control and used it to manoeuvre the trams and the tracks," Miroslaw Micor, a spokesman for Lodz police, told The Daily Telegraph.
"He treated it like any other schoolboy might a giant train set, but it was lucky nobody was killed."
Micor stated that four trams were derailed and others had to make emergency stops that left passengers hurt. "He clearly did not think about the consequences of his actions," he said.