A downlight apparatus includes a base housing, a light module and a rotation shaft. The base housing has an inner hemisphere surface. The light module has an exterior hemisphere surface. The light module has a light source emitting a light. The rotation shaft has a first end fixed to the light module. The base housing has a shaft hole for the rotation shaft to pass through and rotate in the shaft hole. The rotation shaft has a second end attached to the base housing. A rotation axis of the rotation shaft is aligned with a radial direction of the exterior hemisphere surface for changing a light direction of the light by rotating the light module along the rotation shaft.