An electronic device and a component module thereof are provided, wherein the electronic device includes a housing, a component and a flexible substrate. The housing has a mounting region, and the component is disposed in the mounting region. The flexible substrate includes a bonding portion and an extending portion, wherein the bonding portion is disposed between the component and a carrying surface of the mounting region. The mounting portion has a first surface and a second surface opposite to the first surface, wherein the first surface is bonded to the component, and the second surface is bonded to the carrying surface. The extending portion is connected to the bonding portion and extended to the outside of the mounting region.