There are provided calcium hydroxide having a large specific surface area, a resin composition comprising the calcium hydroxide and having excellent thermal stability, and a molded article and a stabilizer for synthetic resins which comprise the calcium hydroxide.There are provided a calcium hydroxide compound represented by the following formula (1): Ca(OH)2-nx(An−)x  (1) (wherein n represents an integer of 1 to 4, x represents a number of 0.001 to 0.2, and An− represents an anion derived from at least one compound selected from the group consisting of a silicon-based compound, a phosphorus-based compound, an aluminum-based compound, an inorganic acid and an organic acid.), and a synthetic resin, a molded article and a stabilizer for synthetic resins which comprise the compound.