PROBLEM TO BE SOLVED: To provide a technology which enhances herbicidal effect by an interrow rotor without reducing work efficiency in herbicidal work in a weeder for a paddy field, which comprises the interrow rotor for weeding an interrow space of seedlings.SOLUTION: A weeder for a paddy field of the present invention comprises: a swing tooth for weeding a space between seedlings; an interrow rotor for weeding an interrow space while rotating; and a rotor position adjustment mechanism having a rotor operation part. The rotor position adjustment mechanism displaces a relative position of the interrow rotor in a vertical direction with respect to the swing tooth by operating the rotor operation part without using a tool or removing a component. This allows a change in a depth, in which the interrow rotor acts on a field, according to a root-taking state of the seedlings and a state of the field, with a one-touch operation. Thus, the height of the interrow rotor can be adjusted easily and quickly. As a result
