With non-contact and contact IC chips becoming common, it is necessary to mass-produce enormous amount of IC chips, which are utilizable for human beings, animals and plants, commercial products, banknotes, and the like, at low cost. For example, it is necessary to manufacture IC chips to be applied to commercial products, banknotes, and the like at a cost of 1 to several yen per IC chip, preferably, at a cost less than 1 yen, and it is desired to realize a structure of an IC chip that can be mass-produced at low cost and a manufacturing process of the IC chip.A method of manufacturing a thin film integrated circuit device according to the present invention includes steps of forming a peel-off layer over a thermally oxidized silicon substrate, forming a plurality of thin film integrated circuit devices over the peel-off layer with a base film interposed therebetween, forming a groove between the plurality of thin film integrated circuit devices, and separating the plurality of thin film integrated circuit devices by introducing one of a gas and a liquid including halogen fluoride into the groove to remove the peel-off layer.