Transmission mechanism device and drive device

A transmission mechanism device comprising:

• a transmission mechanism including a hollow first shaft with a central axis as a center extending along a horizontal plane, a first gear provided on an outer peripheral face of the first shaft, and a first bearing supporting an outer peripheral face of the first shaft;
• a housing that accommodates the transmission mechanism;
• oil contained in the housing;
• and
• an oil passage through which the oil passes,
• wherein
• a first bearing holder portion that holds the first bearing is provided on an inner face of the housing,
• the first bearing holder portion has
• a facing face facing an end face of the first shaft,
• a first holding tubular portion that holds, from radially outside, the first bearing protruding one side in the axial direction from the facing face, and
• a first rib located inside the first holding tubular portion and protruding one side in the axial direction from the facing face,
• the first rib extends in a concave shape that opens upward,
• a lower end of an inner peripheral face of the first rib is located below an upper end of an inner peripheral face of the first shaft when viewed from the axial direction, and
• at least one of one end portion of the first rib in an extending direction or the other end portion in the extending direction faces an inner peripheral face of the first holding tubular portion via a gap when viewed from the axial direction.