Oklo Constraint on the Time-Variability of the Fine-Structure Constant

The Oklo phenomenon, natural fission reactors which had taken place in Gabon about 2 billion years ago, porvides one of the most stringent constraints on the possible time-variability of the fine-structure constant $\alpha$. We first review briefly what it is and how reliable it is in constraining $\alpha$. We then compare the result with a more recent result on the nonzero change of $\alpha$ obtained from the observation of the QSO absoorption lines. We suggest a possible way to make these results consistent with each other in terms of the behavior of a scalar field which is expected to be responsible for the accelaration of the universe.