A microwave oven, comprising: a cavity assembly with a cooking chamber provided therein; a cooling fan assembly provided at a side of the cavity assembly and generating airflow for cooling an electric part; and a heater assembly including: a ceramic heater and a halogen heater provided at a side of the cavity assembly and providing heat to be transferred into the cavity assembly, a heater supporter fixed to a side of the cavity assembly with the ceramic and halogen heaters (41, 42) fixed to the heater supporter, a reflection plate provided above the ceramic and halogen heaters (41, 42) to reflect heat of the ceramic and halogen heaters (41, 42) to the cooking chamber, wherein a portion of the reflection plate corresponding to the ceramic heater is open in its longitudinal direction, and a heater cover for covering the ceramic and halogen heaters (41, 42) to prevent heat of the ceramic and halogen heaters (41, 42) from being transferred to the outside of the cooking chamber, the heater cover being provided above the reflection plate, characterized in that a heater duct is provided above the heater cover, and a channel is defined between an outer surface of the heater cover and an inner surface of the heater duct (48so that a portion of the airflow generated by the cooling fan assembly flows in the channel between the heater cover and the heater duct, thereby indirectly dissipating heat of the ceramic and halogen heaters. a cavity assembly with a cooking chamber provided therein; a cooling fan assembly provided at a side of the cavity assembly and generating airflow for cooling an electric part; and a heater assembly including: a ceramic heater and a halogen heater provided at a side of the cavity assembly and providing heat to be transferred into the cavity assembly, a heater supporter fixed to a side of the cavity assembly with the ceramic and halogen heaters (41, 42) fixed to the heater supporter, a reflection plate provided above the ceramic and halogen heaters (41, 42) to reflect heat of the ceramic and halogen heaters (41, 42) to the cooking chamber, wherein a portion of the reflection plate corresponding to the ceramic heater is open in its longitudinal direction, and a heater cover for covering the ceramic and halogen heaters (41, 42) to prevent heat of the ceramic and halogen heaters (41, 42) from being transferred to the outside of the cooking chamber, the heater cover being provided above the reflection plate, characterized in that a heater duct is provided above the heater cover, and a channel is defined between an outer surface of the heater cover and an inner surface of the heater duct (48so that a portion of the airflow generated by the cooling fan assembly flows in the channel between the heater cover and the heater duct, thereby indirectly dissipating heat of the ceramic and halogen heaters. a ceramic heater and a halogen heater provided at a side of the cavity assembly and providing heat to be transferred into the cavity assembly, a heater supporter fixed to a side of the cavity assembly with the ceramic and halogen heaters (41, 42) fixed to the heater supporter, a reflection plate provided above the ceramic and halogen heaters (41, 42) to reflect heat of the ceramic and halogen heaters (41, 42) to the cooking chamber, wherein a portion of the reflection plate corresponding to the ceramic heater is open in its longitudinal direction, and a heater cover for covering the ceramic and halogen heaters (41, 42) to prevent heat of the ceramic and halogen heaters (41, 42) from being transferred to the outside of the cooking chamber, the heater cover being provided above the reflection plate, characterized in that a heater duct is provided above the heater cover, and a channel is defined between an outer surface of the heater cover and an inner surface of the heater duct (48so that a portion of the airflow generated by the cooling fan assembly flows in the channel between the heater cover and the heater duct, thereby indirectly dissipating heat of the ceramic and halogen heaters.