The partial half-life of $^{190}$Pt for the alpha decay to the first excited level ($E_{exc}=137.2$ keV) of $^{186}$Os was measured using an ultralow-background HPGe-detector system located 225 m underground in the laboratory HADES (Belgium). A sample of high purity platinum (the purity grade is 99.95%) with a mass of 148.122 g was used and measured during 373 days. Preliminary, the partial half-life of $^{190}$Pt is estimated as $T_{1/2}= [2.28 _{-0.16}^{+0.19} (stat.)\pm 0.9(syst.)] \times 10^{14}$ yr.