We investigate a resonant particle production of a scalar field $��$ coupled non-minimally to a spacetime curvature $R$ ($��R ��^2$) as well as to an inflaton field $��$ ($g^2��^2��^2$). In the case of $g < 3 \times 10^{-4}$, $��$ effect assists $g$-resonance in certain parameter regimes. However, for $g > 3 \times 10^{-4}$, $g$-resonance is not enhanced by $��$ effect because of $��$ suppression effect as well as a back reaction effect. If $��\approx -4$, the maximal fluctuation of produced $��$-particle is $\sqrt{< ��^2 >}_{max} \approx 2 \times 10^{17}$ GeV for $g < 1 \times 10^{-5}$, which is larger than the minimally coupled case with $g \approx 1 \times 10^{-3}$.

33pages, 12figures. to appear in Physical Review D