of 1 1 u03bcm these droplets were introduced into a four necked flask of 1 l provided with a thermometer a stirrer a dropping funnel and a cooling tube heated and held at 50 u00b0 c for 15 minutes and rapidly cooled to 20 u00b0 c so that thereafter a mixture of 16 4 g of hexamethylenediamine and 80 g of ion exchange water was dropped into the flask from the dropping funnel over 30 minutes and the droplets were aged at the current temperature for one hour after the dropping the droplets were filtered washed and thereafter dried to obtain capsular particles containing 101 g of the coloring material coloring material capsular particles were prepared similarly to preparation example 5 except that the photochromic coloring material was replaced by that expressed in the above formula 2 coloring material capsular particles were prepared similarly to preparation example 5 except that the photochromic coloring material was replaced by that having a structure expressed in the following chemical formula 3 str3 200 g of the pigment paste obtained in preparation example 1 100 g of a 10 aqueous solution of pva povar 217 product by kuraray co ltd 100 g of a 10 aqueous solution of pva povar 420 product by kuraray co ltd 40 g of a 10 aqueous solution of hydroxypropyl cellulose hpc l product by nippon soda co ltd and 400 g of ion exchange water were mixed with each other.