A binder composition for self-curing mold formation, comprising at least one condensate (A) selected from furfuryl alcohol condensate and furfuryl alcohol/formaldehyde condensate, and an acid-curable resin (B), wherein about the condensate(s) (A), the presence ratio by mole of its/their furan rings (a) to the total of its/their methylol groups (b), methylene groups (c) and oxymethylene groups (d), a:(b+c+d), is from 1:1.00 to 1:1.08, and the content by percentage of the at least one condensate (A) is from 0.3 to 8.0% by weight.