[Problems] The present invention provides a highly marketable reversibly color changeable composition which provides a vivid yellow to orange color during color development, turns colorless during decoloration, and improves light resistance and a reversibly thermochromic microcapsule pigment encapsulating the same.
[Solution] Disclosed are a reversibly thermochromic composition including: (a) a specific pyridine derivative as an electron-donating color-developing organic compound; (b) an electron-accepting compound; and (c) a reaction medium which reversibly induces an electron transfer reaction between the component (a) and the component (b) in a specific temperature range, and a reversibly thermochromic microcapsule pigment encapsulating the same.