An aroma-diffusing heating device using an aroma capsule is provided, including a hollow housing, a heat conduction container and a heating element. The heat conduction container is disposed in the hollow housing. The heating element is disposed on a bottom side of the heat conduction container. The heat conduction container has an aroma capsule placed therein from a free end thereof. The hollow housing has a funnel-shaped space formed between a slanting slide portion and a protruding edge of a disposable container of the aroma capsule to define an operation space. A user is allowed to grab the protruding edge of the aroma capsule with his fingers and place the aroma capsule in the heat conduction container, and his fingers can slide through the slanting slide portion into the operation space. Therefore, the fingers can enter into and leave from the operation space easily.