Provided is a manufacturing method of a sensor including the following steps. A mold having a cavity is provided. At least one chip is disposed in the cavity. The chip has an active surface and a back surface opposite to each other. The active surface faces toward a bottom surface of the cavity. A polymer material is filled in the cavity to cover the back surface of the chip. A heat treatment is performed, such that the polymer material is solidified to form a polymer substrate. A mold release treatment is performed to isolate the polymer substrate from the cavity. A plurality of conductive lines are formed on a first surface of the polymer substrate. The conductive lines are electrically connected with the chip.