1. A suction nozzle used in a mounting device for mounting a component on a board, comprising:an air pipe; and
a suction pad portion which has a flow path communicating with the air pipe, has a cavity portion between the suction pad portion and the component, abuts on the component, and is formed to be larger than the air pipe at a tip of the air pipe,
wherein a resistance cavity which causes resistance and decreases air flow speed when a positive pressure is applied is formed between the flow path and the cavity portion,
wherein the resistance cavity includes a first cavity having a slit shape which has a width smaller than a size of the flow path and a length longer than a size of the flow path, and a second cavity formed on a side of the cavity portion, the second cavity having a slit shape which has a sectional area larger than that of the first cavity, and
wherein the length and width are perpendicular to the flow path in the air pipe.