A fluid dynamic bearing mechanism includes a stationary bearing portion including a sleeve portion, and a rotating bearing portion including an outer rotating portion. A lubricating oil is arranged between the stationary and rotating bearing portions. A first dynamic pressure groove array is arranged in an upper surface of the sleeve portion or a lower surface of the outer rotating portion. A second dynamic pressure groove array is arranged in a surface of the outer rotating portion or a surface of the stationary bearing portion in a region between the first array and a liquid surface. An end of the second array closer to the liquid surface is arranged radially inward of an opposite end of the second array. An upper end opening of a communicating channel defined in the sleeve portion is arranged radially outward of a radially inner end of the first array.