A 55-year-old straphanger was slashed across the neck with a knife during an unprovoked attack on a Queens subway platform, police said.

The assault took place on the “7 line” platform at Roosevelt Avenue and 74th Street in Jackson Heights at 7:20 a.m. Saturday, the NYPD said.

The victim was transported to Elmhurst Hospital with non-life-threatening injuries, cops said. There are no arrests.

Police are looking for a man wearing a blue shirt and jeans, authorities said.