Abstract Photochromic fulgides with a bulky 1-alkyl-1-indolylmethylidene and/or a bulky alkylidene substituent were synthesized and their photochromic as well as absorption spectroscopic properties were compared with those of the known prototype indolylfulgide, 3-[1-(1,2-dimethyl-3-indolyl)ethylidene]-4-isopropylidenedihydro-2,5-furandione. An increase in steric bulkiness of the alkyl group (R1) on the indolylmethylidene group increased the coloring quantum yield (ΦEC = 0.046 (R1 = methyl) to 0.31 (R1 = isopropyl)), whereas an increase in the steric bulkiness of the other alkylidene group (R2) increased the bleaching quantum yield (ΦCE = 0.051 (R2 = isopropylidene) to 0.42 (R2 = 2-adamantylidene)). When both R1 and R2 were bulky, however, the coloring quantum yield was not large, although the bleaching quantum yield was still large. When the methyl group on the 2-position of the indole ring was substituted with an ethyl group, the absorption maximum of the colored form showed a 32-nm bathochromic shift.