A detection sensor for conducting a detection action on the basis of a setting information set by a setting means, comprising: - a detecting means configured to detect a physical value change in a detection area; - an outputting means (20, 21) configured to output an output signal (Sb, Sc) based on a detection result of said detecting means; - an external connecting terminal (15c, 15d) configured to be electrically connectable to a connecting terminal of a first external device, for outputting an output signal (Sc, Sd) from said outputting means (20, 21) to the present said first external device; and said detection sensor further comprising: - said setting means, the setting means being configured to set a setting information pertaining to a detection action; wherein said external connecting terminal (15c, 15d) is electrically connectable to a connecting terminal of an a second external device, for setting information output for outputting said setting information, said detection sensor further comprising: - an inputting means connected to said external connecting terminal; - a selecting means (21 a, 22a) for selectively enabling an output action of said outputting means and an input action of said inputting means; and - a controlling means for, when the second external device for setting information output is connected to said external connecting terminal and said setting information is output from the present said second external device for setting information output, acquiring the present setting information from said second external device by means of enabling an input action of said inputting means with said selecting means (21 a, 22a), and setting the setting information in said setting means, characterized in that said external connecting terminal (15c, 15d) is configured to be electrically connectable to a connecting terminal of another detection sensor; and the detection sensor further comprises: - a switching means configured to selectively switch the detection sensor from a master mode when preferred to be functioning as a copy source to a slave mode when preferred to be functioning as a copy destination, wherein said controlling means is configured to: - function as said second external device for setting information output when it is switched to the master mode by the switching means, and is configured to output its own setting information from said external connecting terminal (15c, 15d) by enabling an output action of said outputting means,causing said setting information to be given to the external connecting terminal of the other detection sensor, and, - when it is switched to the slave mode by said switching means, is configured to acquire said setting information from said other sensor via its own external connecting terminal by means of enabling an input action of said inputting means. - a detecting means configured to detect a physical value change in a detection area; - an outputting means (20, 21) configured to output an output signal (Sb, Sc) based on a detection result of said detecting means; - an external connecting terminal (15c, 15d) configured to be electrically connectable to a connecting terminal of a first external device, for outputting an output signal (Sc, Sd) from said outputting means (20, 21) to the present said first external device; and - said setting means, the setting means being configured to set a setting information pertaining to a detection action; - an inputting means connected to said external connecting terminal; - a selecting means (21 a, 22a) for selectively enabling an output action of said outputting means and an input action of said inputting means; and - a controlling means for, when the second external device for setting information output is connected to said external connecting terminal and said setting information is output from the present said second external device for setting information output, acquiring the present setting information from said second external device by means of enabling an input action of said inputting means with said selecting means (21 a, 22a), and setting the setting information in said setting means, - a switching means configured to selectively switch the detection sensor from a master mode when preferred to be functioning as a copy source to a slave mode when preferred to be functioning as a copy destination, - function as said second external device for setting information output when it is switched to the master mode by the switching means, and is configured to output its own setting information from said external connecting terminal (15c, 15d) by enabling an output action of said outputting means,causing said setting information to be given to the external connecting terminal of the other detection sensor, and, - when it is switched to the slave mode by said switching means, is configured to acquire said setting information from said other sensor via its own external connecting terminal by means of enabling an input action of said inputting means.