a light - guiding device applicable to a panel having at least a through hole includes a sleeve part and a light guide . the sleeve part is able to be mounted on the through hole , and includes a first combining portion and a positioning portion corresponding to the panel for positioning the sleeve portion on the panel . the light guide includes a second combining portion for engaging with the first combining portion , so as to fix the light guide on the panel in cooperation with the sleeve part , allowing an assembling / disassembling process of the light - guiding device to be easily performed .