  We study the superradiance instability of charged massive scalar field in the
background of Kerr-Newman-anti-de Sitter black hole. By employing the
asymptotic matching technique to solve Klein-Gordon equation analytically, the
complex parts of quasinormal frequencies are shown to be positive in the regime
of superradiance. Because the calculation is performed in the approximation of
small black hole, the result indicates that small Kerr-Newman-anti-de Sitter
black hole is unstable against the massive scalar field perturbation with small
charge.
