Rail-guided cart system and branching control method for a rail-guided cart system

In the disclosed rail-guided cart system, a rail-guided cart, provided with a left-right pair of up-down rollers that can move freely up and down, is driven along a track provided with a left-right pair of guides that can have two different protrusion lengths, long and short. The up-down rollers can be switched freely between a state wherein both are in a neutral position and a state wherein one is in an advanced position and one is in a recessed position. An up-down roller in the neutral position is guided only by long guides, an up-down roller in the advanced position is guided by both long and short guides, and an up-down roller in the recessed position is guided by no guides. One track branches into a first branch section and a branch/merge section, and the branch/merge section merges into a straight section of another track. Long guides are used in the branch/merge section, and at least on the sides opposite the branch/merge section, the first branch section and the straight section use short guides. Whe