A can-type heat exchanger comprising: a housing of which a first surface is opened and a second surface is closed and having a space therein, integrally formed with a mounting portion provided in a lateral side and communicated with the space, and a first inlet and a first outlet provided in the mounting portion and the lateral side thereof; a partition wall integrally formed to the housing, separating the space and the inside of the mounting portion, connected to the first inlet and the first outlet, and forming a bypass passageway inside of the housing; a heat radiating unit inserted into the space, provided with connecting lines alternately formed by stacking a plurality of plates, one of the connecting lines communicating with the space, and where the operating fluids are heat-exchanged with each other while passing through the respective connecting lines; a cover cap mounted at the opened first surface of the housing so that the heat radiating unit integrally mounted on one surface thereof to the space, and a second inlet and a second outlet for communicating with the other connecting line of the connecting lines, are formed in the cover cap at the first surface; and a valve unit that is mounted at the first inlet formed in the mounting portion and penetrating the partition wall in the mounting portion, selectively opening and closing the space or the bypass passageway separated by the partition wall using linear displacement which is generated when expansion and contraction occur according to the temperature of the coolant flowing from the first inlet, and adjusting flow of the operating fluids. a housing of which a first surface is opened and a second surface is closed and having a space therein, integrally formed with a mounting portion provided in a lateral side and communicated with the space, and a first inlet and a first outlet provided in the mounting portion and the lateral side thereof; a partition wall integrally formed to the housing, separating the space and the inside of the mounting portion, connected to the first inlet and the first outlet, and forming a bypass passageway inside of the housing; a heat radiating unit inserted into the space, provided with connecting lines alternately formed by stacking a plurality of plates, one of the connecting lines communicating with the space, and where the operating fluids are heat-exchanged with each other while passing through the respective connecting lines; a cover cap mounted at the opened first surface of the housing so that the heat radiating unit integrally mounted on one surface thereof to the space, and a second inlet and a second outlet for communicating with the other connecting line of the connecting lines, are formed in the cover cap at the first surface; and a valve unit that is mounted at the first inlet formed in the mounting portion and penetrating the partition wall in the mounting portion, selectively opening and closing the space or the bypass passageway separated by the partition wall using linear displacement which is generated when expansion and contraction occur according to the temperature of the coolant flowing from the first inlet, and adjusting flow of the operating fluids.