The present invention provides a photochromic compound that is colored
when irradiated with visible light and quickly faded when set in a dark
place. The photochromic compound according to the present invention is
expressed by the following general formula (I): ##STR00001## where each
of A.sub.1, A.sub.2 and A.sub.3 is a five-member rings forming a
6.pi.-electron system, the three rings being identical, partially
identical or totally different from each other, and each ring may have a
substituent; B.sub.1 and B.sub.2 are functional groups, each having an
atomic number of five or larger, including a ring compound, and bonded to
the 2-carbon of each of A.sub.2 and A.sub.3, respectively; and R.sub.1,
R.sub.2 and R.sub.3 are substituents identical to or different from each
other. This compound is highly colorable and durable even when it is
dispersed into plastic macromolecular materials. Therefore, it is
suitable as a dye material for sunglasses or similar products.