We conducted thermal analyses and cooling tests of the space observation camera (SOC) of the multi-purpose infrared imaging system (MIRIS) to verify passive cooling. The thermal analyses were conducted with NX 7.0 TMG for two cases of attitude of the MIRIS: for the worst hot case and normal case. Through the thermal analyses of the flight model, it was found that even in the worst case the telescope could be cooled to less than $206^{circ}K$. This is similar to the results of the passive cooling test (${sim}200.2^{circ}K$). For the normal attitude case of the analysis, on the other hand, the SOC telescope was cooled to about $160^{circ}K$ in 10 days. Based on the results of these analyses and the test, it was determined that the telescope of the MIRIS SOC could be successfully cooled to below $200^{circ}K$ with passive cooling. The SOC is, therefore, expected to have optimal performance under cooled conditions in orbit.