A packed frozen sushi product comprising a vacuumed, frozen and hermetically sealed flexible plastic bag; an open-topped plastic box placed in the bag; and a frozen sushi product contained in the box; in the plastic bag, the box and the frozen sushi product being frozen together in a unified form, the packed frozen sushi product thereby being adapted for microwave cooking. Water vapor emanating from the sushi product in thawing is allowed to flow through a space formed around the sushi material to heat a shaped rice section and a material or materials, thereby diminishing unevenness in temperature distribution after thawing. By virtue thereof, a packed frozen sushi product suitable for mass production is provided.