A lamp-based aroma diffuser using an aroma capsule is disclosed to include a lamp housing, a hollow light-transmissive shade mounted in the lamp housing, a holder member mounted in the lamp housing, a heat conduction device mounted in the holder member, a heating element kept in contact with the bottom wall of the heat conduction device, a light-emitting device, and a power supply device-incorporated PC board for driving the heating element to heat the heat conduction device and a replaceable aroma diffuser in the heat conduction device and the light-emitting device to emit color light through the hollow light-transmissive shade and the lamp housing.