A dead man was found inside a subway car on the Upper East Side on Monday morning, police said.

The unidentified man, who was approximately 40 to 50 years old, was discovered unresponsive inside the northbound Q-train at the 96th Street Subway Station just before 9:30 a.m.

There were no obvious signs of trauma, and he was pronounced dead at the scene, authorities said.

The city’s medical examiner will determine the cause of death.