A horizontal conveying carriage includes: a carriage body including: a base part; a drive wheel; and a steering wheel; a forklift attached to the carriage body, and configured to pick up a conveyed object and unload the conveyed object; an extending and shrinking mechanism configured to extend and shrink the forklift in a front-and-rear direction; a lifting and lowering mechanism configured to lift and lower the forklift in a vertical direction; a supporting mechanism configured to support the forklift from a lower side; an own position estimation unit configured to estimate an own position of the carriage body; a positional relation recognition unit configured to recognize a positional relation between the own position and the conveyed object; and a control unit configured to control movement of the carriage body and to control an operation of the forklift based on the own position and the positional relation.