A medical device including a heating unit (1, 2, 122 K) provided on a distal side of a catheter to heat a biological tissue and a hand-side steering unit provided at a proximal portion of the catheter to steer advance and retraction operation with respect to the catheter at the heating unit (1, 2, 122 K), the hand-side steering unit comprises: a main body portion (71, 132) interlocked with the catheter; a slide portion (100, 33) which is interlocked with the heating unit (1, 2, 122 K) and which is approachable and separable with respect to the main body portion (71, 132); a guide unit (40 A, 50, 131) which is interlocked movably with one of the main body portion (71, 132) and the slide portion (100, 133) and also which is fixed on the other thereof; and an input connector (75, 134) which is provided at the main body portion (71, 132) or, the slide portion (100, 133), which is electrically connected with the heating unit (1,2, 122 K) and also with which an output connector (55, 87, 136) for supplying electric energy is connectable, characterized in that the guide unit (40 A, 50, 131), is arranged at a position for hindering connection between the input connector (75, 134) and the output connector (55, 87, 136) and also, there is provided a connection adjusting unit (41, 51) which is a notch or a through-hole for enabling connection between the input connector (75, 134) and the output connector (55, 87, 136) when the heating unit (1, 2, 122 K) moved to a position at which the biological tissue is heatable by moving the slide portion (100, 133) with respect to the main body portion (71, 132); wherein the connection adjusting unit (41, 51) is formed on the guide unit (40 A, 50, 131); and wherein an outer circumferential surface of the outer connector contacts a side surface of the connection adjusting unit (41, 51) when the heating unit (1,2, 122 K) moved to the position at which the biological tissue is heatable by moving the slide portion (100, 133) with respect to the main body portion (71, 132). a main body portion (71, 132) interlocked with the catheter; a slide portion (100, 33) which is interlocked with the heating unit (1, 2, 122 K) and which is approachable and separable with respect to the main body portion (71, 132); a guide unit (40 A, 50, 131) which is interlocked movably with one of the main body portion (71, 132) and the slide portion (100, 133) and also which is fixed on the other thereof; and an input connector (75, 134) which is provided at the main body portion (71, 132) or, the slide portion (100, 133), which is electrically connected with the heating unit (1,2, 122 K) and also with which an output connector (55, 87, 136) for supplying electric energy is connectable, characterized in that the guide unit (40 A, 50, 131), is arranged at a position for hindering connection between the input connector (75, 134) and the output connector (55, 87, 136) and also, there is provided a connection adjusting unit (41, 51) which is a notch or a through-hole for enabling connection between the input connector (75, 134) and the output connector (55, 87, 136) when the heating unit (1, 2, 122 K) moved to a position at which the biological tissue is heatable by moving the slide portion (100, 133) with respect to the main body portion (71, 132); wherein the connection adjusting unit (41, 51) is formed on the guide unit (40 A, 50, 131); and wherein an outer circumferential surface of the outer connector contacts a side surface of the connection adjusting unit (41, 51) when the heating unit (1,2, 122 K) moved to the position at which the biological tissue is heatable by moving the slide portion (100, 133) with respect to the main body portion (71, 132).