In bearing mechanism for a motor spinning a storage disk about a center axis, an interference-fit portion of a shaft is interference-fitted into a through hole of a bushing from an axial lower side thereof such that the shaft is fixed to a rotor hub. The interference-fit portion of the shaft is defined with an upper section, a lower section, and a concave portion. When the shaft is interference-fitted into the bushing, the upper and lower sections engage with the bushing, and the concave portion radially faces an inner surface of the bushing with a gap defined therebetween.