To provide an oven with a steam generator without causing uneven application of steam onto an object to be baked.

The steam generator 40A for supplying steam into the baking oven 20 is equipped with a water supply passage 44A for supplying water into a steam generation tank 41A and a drain passage 46A for draining water un-evaporated in the steam generation tank 41A. A second drain pipe 46Ab of the drain passage 46A is composed so as to have a smaller inside diameter than that of the water supply passage 44. Thereby, the water un-evaporated in the steam generation tank 41A is scarcely drained to increase the pressure in the steam generation tank 41A. As a result, the steam is violently delivered from an upper slit 41Aa of the steam generation tank 41A to thereby supply the steam even to the front of an upper baking oven 20A which is farther from the steam generation tank 41A and eliminate the unevenness of application of steam.