PROBLEM TO BE SOLVED: To provide a weed-proofing construction method of a road joint for safely and efficiently removing weeds or a drain ditch cleaning method and a foreign substance removing device.SOLUTION: Between a passing lane 3 and a central traffic strip 4, a semi-self-propelled weeder 11 operated by an operator 31 and a hand-pushed silica sand/weed-proof material supplier 12 moved by an operator 32 are disposed. In a lower part of a left front side of the weeder 11, a rotary brush 15 and a brush cover 16 which covers an upper half of the rotary brush 15 are mounted. In a front part of the brush cover 16, a vacuum hose 17 is connected and weeds 9 or the like removed/discharged by the rotary brush 15 are sucked by negative pressure. The silica sand/weed-proof material supplier 12 includes a tank or a pump for storing a main agent of an ester-based elastic resin and a hardener in addition to silica sand, press-feeds silica sand into a silica sand injector 18 held by a worker 33, and press-feeds the main
