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We have determined the wavelength dependence of the extinction in thenear-infrared bands ($J$, $H$, $K_{\mathrm S}$) toward the Galactic center fromthe VVV (VISTA Variables in the V\'ia L\'actea) aperture photometry of thestars in the region $|l|\lesssim2^\circ.0$ and$0^\circ.5\lesssim|b|\lesssim1^\circ.0$; this region consists of 12 VVV tiles.We have found significant systematic discrepancy up to $\sim0.1$ mag betweenthe stellar magnitudes of the same stars in overlapping VVV tiles. However, bycarefully using the positions of red clump stars in color-magnitude diagrams asa tracer of the extinction and reddening, we are able to determine the averageof the ratios of total to selective extinction to be $A(K_{\mathrmS})/E(H-K_{\mathrm S})=1.44\pm0.04$, $A(K_{\mathrm S})/E(J-K_{\mathrmS})=0.423\pm0.024$, $A(H)/E(J-H)=1.25\pm0.04$; from these ratios, a steep powerlaw $A(\lambda)\propto\lambda^{-\alpha}$ whose index $\alpha$ is $\sim2.0-2.3$in the $J,H,K_{\mathrm S}$ wavelength range is estimated. The obtainedwavelength dependence is consistent with those obtained with the MKOphotometric system employed in SIRIUS camera attached to the IRSF telescope inprevious studies. Such a steep decline of extinction toward the longerwavelengths is also in line with recent results based on deep imaging surveys.The determined extinction law seems to be variable in the VVV tile to tile, andit is not clear how much of this is due to real sight line variations and dueto observational systematic effects. Thus, there might be room for improvementof the extinction law determination from the existing VVV data, but this steepextinction law tends to locate heavily reddened objects in the Galactic planemore distant from us when their distance moduli are calculated from theobserved reddening values.

Interstellar Extinction Law toward the Galactic Center IV: J, H, and Ks Bands from VVV Red Clump Stars