  JWST observed the magnetar 4U 0142+61 with the MIRI and NIRCam instruments
within a 77 min time interval on 2022 September 20-21. The low-resolution MIRI
spectrum and NIRCam photometry show that the spectrum in the wavelength range
1.4-11 $\mu$m range can be satisfactorily described by an absorbed power-law
model, $f_{\nu}\propto \nu^{-\alpha}$, with a spectral slope $\alpha
=0.96\pm0.02$, interstellar extinction $A_V= 3.9\pm0.2$, and normalization $f_0
= 59.4\pm 0.5$ $\mu$Jy at $\lambda = 8$ $\mu$m. These observations do not
support the passive disk model proposed by Wang et al. (2006), based on the
Spitzer photometry, which was interpreted as evidence for a fallback disk from
debris formed during the supernova explosion. We suggest a nonthermal origin
for this emission and source variability as the most likely cause of
discrepancies between the JWST data and other IR-optical observing campaigns.
However, we cannot firmly exclude the presence of a large disk with a different
dependence of the effective disk temperature on distance from the magnetar.
Comparison with the power-law fit to the hard X-ray spectrum above 10 keV,
measured by NuSTAR contemporaneously with JWST, shows that the X-ray spectrum
is significantly harder. This may imply that the X-ray and IR nonthermal
emission come from different sites in the magnetosphere of the magnetar.
