Carrier with retractable wheels

1. A carrier with retractable wheels, comprising:

a main body including a storage space and an inlet hole formed in a bottom to be open or closed by a sliding plate;

a moving unit having a body pivotably provided in the inlet hole and a wheel attached to an end of the body, wherein when the inlet hole is closed by the sliding plate, the moving unit is pivoted up, the wheel is supported by the sliding plate to be positioned inside the inlet hole and, when the inlet hole is open, the moving unit is pivoted down to stick out of the inlet hole;

a fastening member pivotably provided in the inlet hole in a position eccentric from the body, wherein the fastening member, together with the body, is pivoted down to come in tight contact with the body in parallel with the body to support the body; and

a brush attached to a lower end of the fastening member and positioned to contact the wheel when the fastening member and the body are in contact with each other, wherein the body includes a first fixing hole formed in a first side thereof, and the fastening member includes a first fixing protrusion at an end thereof, wherein in a position where the body and the fastening member together are pivoted down and contact each other, the first fixing protrusion is fitted into the first fixing hole, and wherein the body further includes a second fixing hole formed in a second side thereof, and the sliding plate includes a second fixing protrusion fitted into the second fixing hole to fasten the body pivoted down when the sliding plate opens the inlet hole.