A cooker comprising: a heating chamber configured to accommodate and heat an object; a microwave-heating mechanism configured to form microwaves and radiate the microwaves into the heating chamber to heat the object with a microwave-heating mode; a convection-heating mechanism configured to heat the object with a convection mode; and a microwave leak suppression mechanism configured to suppress a microwave leak, wherein the convection-heating mechanism includes: a circulation fan for taking air from the heating chamber and for blowing the air into the heating chamber; a convection heater for heating the air taken from the heating chamber by the circulation fan; and a hot air guide (43, 44) for guiding the air taken from the heating chamber by the circulation fan toward the convection heater, and for guiding a direction of the hot air blown into the heating chamber by the circulation fan to a desired position in the heating chamber; and a fan driver for driving a circulation fan shaft for rotating the circulation fan, the convection heater and the circulation fan are disposed in a convection forming space that is in communication with the heating chamber, the fan driver is disposed outside of the convection forming space, and the microwave leak suppression mechanism includes a coaxial seal mechanism for forming a gap between the circulation fan shaft passing through a first wall forming the convection forming space and the first wall and setting the gap between opposing faces of the circulation fan shaft and the first wall to a predetermined distance or smaller, and suppresses a microwave leak from the convection forming space, and the cooker further comprises a second wall covering the first wall forming the convection forming space with a space (b) interposed, wherein the circulation fan shaft passes through the first wall and the second wall, and wherein, as the microwave leak suppression mechanism, a metal mesh seal disposed in an annular shape around the circulation fan shaft passing through the second wall is provided on a side of the second wall, on which the fan driver is provided, characterized in that the metal mesh seal is pressed and fixed to the second wall by a seal pressure plate into which the circulation fan shaft passes through, and the seal pressure plate forms a microwave sealing space in the metal mesh seal. a heating chamber configured to accommodate and heat an object; a microwave-heating mechanism configured to form microwaves and radiate the microwaves into the heating chamber to heat the object with a microwave-heating mode; a convection-heating mechanism configured to heat the object with a convection mode; and a microwave leak suppression mechanism configured to suppress a microwave leak, wherein the convection-heating mechanism includes: a circulation fan for taking air from the heating chamber and for blowing the air into the heating chamber; a convection heater for heating the air taken from the heating chamber by the circulation fan; and a hot air guide (43, 44) for guiding the air taken from the heating chamber by the circulation fan toward the convection heater, and for guiding a direction of the hot air blown into the heating chamber by the circulation fan to a desired position in the heating chamber; and a fan driver for driving a circulation fan shaft for rotating the circulation fan, a circulation fan for taking air from the heating chamber and for blowing the air into the heating chamber; a convection heater for heating the air taken from the heating chamber by the circulation fan; and a hot air guide (43, 44) for guiding the air taken from the heating chamber by the circulation fan toward the convection heater, and for guiding a direction of the hot air blown into the heating chamber by the circulation fan to a desired position in the heating chamber; and a fan driver for driving a circulation fan shaft for rotating the circulation fan, the convection heater and the circulation fan are disposed in a convection forming space that is in communication with the heating chamber, the fan driver is disposed outside of the convection forming space, and the microwave leak suppression mechanism includes a coaxial seal mechanism for forming a gap between the circulation fan shaft passing through a first wall forming the convection forming space and the first wall and setting the gap between opposing faces of the circulation fan shaft and the first wall to a predetermined distance or smaller, and suppresses a microwave leak from the convection forming space, and the cooker further comprises a second wall covering the first wall forming the convection forming space with a space (b) interposed, wherein the circulation fan shaft passes through the first wall and the second wall, and wherein, as the microwave leak suppression mechanism, a metal mesh seal disposed in an annular shape around the circulation fan shaft passing through the second wall is provided on a side of the second wall, on which the fan driver is provided, characterized in that the metal mesh seal is pressed and fixed to the second wall by a seal pressure plate into which the circulation fan shaft passes through, and the seal pressure plate forms a microwave sealing space in the metal mesh seal.