A light-guide type illumination device includes a heat-dissipating unit, a conductive unit, a light-emitting unit and a light-guiding unit. The heat-dissipating unit includes a heat-dissipating body. The conductive unit and the light-emitting unit are respectively disposed on a first side and a second side of the heat-dissipating body. The light-emitting unit includes at least one light-emitting element electrically connected to the conductive unit for generating light beams. The light-guiding unit includes at least one light-guiding element disposed above the light-emitting unit. The light-guiding element has a light input surface formed on a bottom side thereof for receiving the light beams and an optical surface-treated layer formed on at least one lateral surface thereof. Hence, the instant disclosure can provide an annular 360-degree light-emitting range by matching the light-emitting unit and the light-guiding unit, thus any type of conventional energy-saving bulb can be replaced by the illumination device.