An aroma-diffusing heating device 1 includes a heating base 10, an aroma capsule 12 detachably accommodated in the heating base 10 and heatable by the heating base 10 to give off fragrance, and a cap 14 capped on the heating base 10 over the aroma capsule 12. The aroma capsule 12 includes a heat-transfer container 120 defining a top opening 1200, an aromatic substance 122 held in the heat-transfer container 120, and a sealing film 124 bonded to the heat-transfer container 120 to seal the aromatic substance 122 in the heat-transfer container 120.