  The JSNS$^2$ experiment is aimed to search for sterile neutrino oscillations
using a neutrino beam from muon decays at rest. The JSNS$^2$ detector contains
17 tons of 0.1\% gadolinium (Gd) loaded liquid scintillator (LS) as a neutrino
target. Detector construction was completed in the spring of 2020. A slow
control and monitoring system (SCMS) was implemented for reliable control and
quick monitoring of the detector operational status and environmental
conditions. It issues an alarm if any of the monitored parameters exceed a
preset acceptable range. The SCMS monitors the high voltage (HV) of the
photomultiplier tubes (PMTs), the LS level in the detector, possible LS
overflow and leakage, the temperature and air pressure in the detector, the
humidity of the experimental hall, and the LS flow rate during filling and
extraction. An initial 10 days of data-taking with a neutrino beam was done
following a successful commissioning of the detector and SCMS in June 2020. In
this paper, we present a description of the assembly and installation of the
SCMS and its performance.
