The title imidazole 1 forms inclusion complexes with ethyl acetate, tert-BuOH, and benzene. The complexes lost their guest molecule to give polymorphic crystals A, B, C and D in a pure state. A is red plates, B is yellow needles, C is pale yellow silky needles and D is light yellow cottony needles. The polymorphic crystal turns to the other one when the crystal contacts with organic vapor. The reactivity decreased with B > D > C > A. Structure and reactivity of the polymorphic crystals are discussed on the type of hydrogen bonding and on molecular arrangements in crystals.