To provide a safe simple coupler for a ride-on toy, which eliminates the risk of pinching a user's foot, even in the case where an angle between the ride-on toy and a rear carriage becomes an acute angle when the ride-on toy turns to the right or left, and which enables an infant to perform a fitting operation for himself/herself.

A coupler for a ride-on toy couples both vehicles together by inserting a coupling rod, which is attached to a ride-on toy, and a coupling rod, which is attached to the other vehicle, into a cylindrical cover, and inserting a pin from an upper part of the cylindrical cover. A hole and a taper for communication of the pin are provided so that the respective coupling rods can move upward, downward, rightward and leftward inside the cylindrical cover.