A case includes a first member and a second member configured in such a way that a closed space is formed between the first and second members in a state where the first and second members abut against each other. The first member includes a shaft portion extending toward the second member. The second member includes a shaft support portion including a circumferential wall portion that surrounds one end portion of the shaft portion. The shaft portion includes an enlarged-diameter portion that is the one end portion melted in such a way as to be enlarged in diameter.