  The pressure dependencies of the magnetic and superconducting transitions, as
well as that of the superconducting upper critical field are reported for
single crystalline EuRbFe$_4$As$_4$. Resistance measurements were performed
under hydrostatic pressures up to 6.21 GPa and in magnetic fields up to 9 T.
Zero-field-cool magnetization measurements were performed under hydrostatic
pressures up to 1.24 GPa under 20 mT applied field. Superconducting transition
temperature, $T_\text c$, up to 6.21 GPa and magnetic transition temperature,
$T_\text M$, up to 1.24 GPa were obtained and a pressure-temperature phase
diagram was constructed. Our results show that $T_\text c$ is monotonically
suppressed upon increasing pressure. $T_\text M$ is linearly increased up to
1.24 GPa. For the studied pressure range, no signs of the crossing of $T_\text
M$ and $T_\text c$ lines are observed. The normalized slope of the
superconducting upper critical field is gradually suppressed with increasing
pressure, which may be due to the continuous change of Fermi-velocity $v_F$
with pressure.
