To mount an eaves gutter joint cover along the outside face of an eaves gutter while holding the joint cover fitted into a joint, to the eaves gutter joint cover covering the outside of the eaves gutter joint even if the joint cover is not provided with an engaging portion between the front and rear lug portions of the eaves gutter.

The bottom face portion 31 of the eaves gutter joint cover 3 made of an elastic member, is mounted to the joint of the eaves gutter 1, while striding over the butting end of the eaves gutter 1 connected by means of a joint member 2, is provided in a bent shape, The opening width between the front face and rear face portions 33 are formed narrower than the opening width between the front face wall and rear face wall of the eaves gutter, widening the width between the front face and rear face to be mounted on the outside face of the eaves gutter.