There is provided a microwavable vacuum-packed frozen sushi product comprising: a flexible plastic packing bag which is vacuumed to a pressure of 50 to 600 mmHg and, in the pressure-reduced state, hermetically sealed; an open-topped plastic box placed in the plastic packing bag; a laminated metal foil placed on the bottom of the plastic box; and a sushi product placed in the plastic box with its sushi material or materials in contact with the laminated metal foil; the microwavable vacuum-packed frozen sushi product being such that an inner surface of the plastic packing bag is in contact with a rice section of the sushi product; and the plastic packing bag, the plastic box, the laminated metal foil and the sushi product are frozen together in a unified form, in which water vapor emanating from the sushi product in the thawing flow through a space formed around the sushi product to effect heating of the rice section and the sushi material or materials of the sushi product, thereby diminishing temperature unevenness in the sushi product after the thawing, and which is suitable for mass production.