A rice transplanter for detecting a field surface with a sensor provided separately from a float and correcting a displacement between the field ground contact surface at which the float is detected and the actual field surface wherein the problem is addressed of providing a technique for improving detection precision and the like with the sensor. A rice transplanter provided with a float for detecting the field ground contact surface is provided with a sensor for detecting the field surface in the direction directly ahead of a planting position the sensor being provided separately from the float. The sensor is provided with a detection unit for following the field surface and a support part for slideably supporting the detection unit and the detection unit is constituted of: a stay connected to the support part a ground contact part extending in a substantially horizontal direction the ground contact part contacting the field surface and an extension part provided between the stay and the ground contact part the extension part being extended in the vertical direction. The shape of the ground contact part is formed such that the bottom part is wide and the top part is narrow.
