He says the companies are to blame for high gas prices.
Speaking Sunday at a gas station on Manhattan's West Side, the Democrat said that "something is rotten." He said refiners' profits have more than doubled since last year.
Meanwhile, the price of unleaded gas went up by almost 12 percent in the two weeks ending May 6.
In New York, the average price for a gallon of gas is $4.03.
In New Jersey it's $3.77.
In Connecticut it's $4.13.
The senator says he believes refiners are fixing prices by cutting back on stockpiles.
In a letter to the Federal Trade Commission, Schumer demanded an investigation into record profits by major refiners.
The letter is also signed by the Senate Majority Leader, Harry Reid, and three other Democratic senators.