A sealing key includes a container and an IC tag component fixed inside the container. The container has a shape that includes a body part and an insertion part that protrudes from the body part. The IC tag component includes a base, an IC chip mounted on the base, and a circuit pattern formed on the base. The circuit pattern includes an antenna structure that is connected to the IC chip to enable the IC chip to perform non-contact communication in. A method for manufacturing the sealing key includes: arranging in a mold a support part that configures a portion of the container; arranging the IC tag component on the support part such that the circuit pattern is positioned being extended across a boundary between the insertion part and the body part; and pouring a resin into the mold to thereby form a resin seal part that configures a portion of the container and seals the IC tag component, such that the resin seal part is joined with the support part.