To easily and inexpensively lay a safe partition line, by using a belt frame which is exposed on a court face at the upper face and buried falt as an installation member for partition lines in a tennis court in which rainwater permeates easily to drain well and detachably sticking a line tape on the belt frame by elastically fitting it with protrusions and recessions and laying the tape so as to be nearly flush with the cour face.

When partition lines are laid on a tennis court in which rainwater permeates easily to drain well, a belt frame 2 molded with plastics is buried and fixed on the expected line of the court so as to expose the upper face by means of projections 3 protruded at the underface, for driving into the ground. And projections 5, 5 turning inward are parallelly formed at both side edges of the belt frame 2 in both sides of a long groove 4 cut on the upper face of the belt frame 2 and a belt-form line tape 6 is laid parallelly on the long groove 4 between the projections 5, 5 and further, protruded edges 6a connected to the lower part of the tape 6 are fitted to the lower part of the projections to stick the line tape 6 covered with the projections 5 of the belt frame, so as to be nearly flush with the court face.