In order to clarify the photobleaching process of the visual pigment rhodopsin by chemical methods, two kinds of rhodopsin analogues [(XIb) and (XII)] were synthesised. The former was derived from 9-cis-retro-γ-retinal (Xb) having two dissected chromophoric systems, one diene and one trienal chromophore. The latter was prepared from 11-cis-locked cyclopentatrienylidene retinal (IV). From the photochemical behaviours of two artificial visual pigments [(XIb) and (XII)] at low temperatures, the conversion of rhodopsin to bathorhodopsin-the primary photochemical event-was confirmed not to involve the proton translocation mechanism but to be caused by the isomerisation of the 11, 12-cis-double bond to trans geometry. Circular dichroism observations in the two 11-cis-fixed-rhodopsin analogues [(XIb) and (XII)] have demonstrated that the origin of the optical activity of rhodopsin in the visible region should be due to the twisted conformation around the 12-13 single bond.