A portable modularized stack device includes a flexible wristband and an electronic module. The flexible wristband has a belt which is embedded with wires therein. The belt has a receiving portion formed thereon, a first connector connected at one end of the belt and a second connector connected at the other end of the belt. The first connector and the second connector are matched correspondingly. The flexible wristband further has a third connector. The electronic module has a fourth connector and is disposed on the receiving portion of the flexible wristband. The fourth connector is connected to the third connector. Thus, the present invention can be varied and expanded by stacking another electronic device thereon, and the flexible wristband can be used as a transmission line.