  We study the multi-wavelength spectral properties of the black hole X-ray
binary MAXI J1348$-$630 using quasi-simultaneous $\textit{ALMA}$,
$\textit{NICER}$, and $\textit{Swift}$ observations during the decay phase of
the January 2019 outburst. In millimeter wavelengths, radio continuum emissions
in the frequency range of 89.56$-$351.44~GHz are measured. We found that the
flux densities at millimeter wavelength varied between 12.18 mJy and 18.47 mJy
with spectral index ($\alpha $) of $0.28\pm 0.02$. The broadband spectrum
suggests that the source was accompanied by weak synchrotron emission from the
compact jets. Broadband spectral study indicates that MAXI J1348--630 falls in
the regime of ``radio-quiet'' during the decay phase of the outburst. The
$\textit{NICER}$ spectrum is fitted by a combined model of disk blackbody
component $(\textit{diskbb})$ along with a comptonization component
$(\textit{simpl})$ which explains the power-law continuum caused by the thermal
Comptonisation of soft disk photons in a hot gas of electrons. The
$\textit{NICER}$ spectrum is dominated by the comptonised components during the
decay phase of the outburst close to the hard state of the source. We have
investigated the correlation between X-ray and radio luminosity using
quasi-simultaneous $\textit{ALMA}$ and $\textit{NICER}$ data to understand the
source nature by locating the source in the $L_{X}$-$L_{R}$ diagram. The
correlation study of radio/X-ray luminosity suggests that MAXI J1348--630 did
not follow the well-known track for black holes and it is a new member of a
restricted group of sources.
