To provide a medical tool with which a puncturing state of a needle can be confirmed by simple constitution.

A catheter 1A is inserted to a living body to be used. The catheter 1A has: a long-length catheter main body 2A; the needle 4A provided at the distal end 22 of the catheter main body 2A; and a detection part 6A which detects the punctuating state of the needle 4A to a desired section 20 in the living body. The detection part 6A has an electrically active polymer 61a where electric potential occurs by deformation and two output terminals 62a and 62b which output the electric potential occurring at the electrically active polymer 61a. A potential difference between the output terminals 62a and 62b is monitored to detect the puncturing state.

COPYRIGHT: (C)2007,JPO&INPIT