Inspired by a recent Furuta's result, we give a generalization of parametrized grand Furuta inequality; if $A \ge B > 0$, then $$A^u\ \sharp_{\frac{\delta-u}{\beta-u}}\ (A^t \natural_{\frac{\beta-t}{p-t}}\ B^{p}) \le (A^{t} \natural_{\frac{\beta-t}{p-t}}\ B^{p})^{\frac{\delta}{\beta}}$$ for $t \in [0,1], 0 \le t < p \le \beta,\ u \le 0\ and\ \delta \in[0,\beta].$ As an application we discuss the monotonicity of an opertor function for $A \ge B$ by $$H_{p,\delta,t}(A,B,u,\beta)=A^{u}\ \sharp_{\frac{\delta-u}{\beta-u}} (A^{t}\ \natural_{\frac{\beta-t}{p-t}}\ B^{p});$$ it is increasing for $u \le 0$ and decreasing for $\beta \ge p$ where $0 \le t < p \le \beta$, $u \le 0$ and $\delta \in [0,\beta]$.\\