To provide a setting retarder for photo-setting concrete, which has high capability of retarding the setting of photo-setting concrete.

This setting retarder consists of a photocurable resin which has a hydrolyzable main chain and the hydrolyzate of which has an acidic group(s) capable of capturing calcium ion, wherein: optionally, the hydrolyzate contains plural acidic groups and of the plural acidic groups, at least one pair of acidic groups have a positional relationship to calcium ion such that the pair of acidic groups, together with the calcium ion, are capable of forming a chelate salt; and also optionally, as an example of the photocurable resin, a polyester resin having photopolymerizable groups, or another resin having photopolymerizable groups such as vinyl, (meth)acryloyl, cinnamoyl or vinylene groups, can be used.