In recent small marine turbochargers many efforts have been made to speed up the rotation of rotor to attain a high pressure-ratio. It is well known that a floating bush bearing has an excellent stability performance in high speed operating conditions. Its performance, however, is largely affected by a significant change of the bush shape with heat deformation and by the operating characteristic conditions due to the temperature of oil film surrounding the bush. In the present investigation, temperature measurements were performed for a small marine turbocharger with a floating bush bearing for 500kW class diesel engines. From the mea-surements, the effects of the operating condition on surrounding temperatures of the bearing were discussed. The results give us a useful knowledge to design next advanced turbochargers with the floating bearing.