An automatic splicing device which connects a first tape and a second tape provided with cavities (Ct1, Ct2) for storing components (e1, e2) and indexing holes (Hc1, Hc2) at fixed intervals using splicing tape, comprising: first and second cutting devices (54, 55) for respectively cutting at first and second cutting positions (Lc1, Lc2) the respective unnecessary sections at the tail end of the first tape and the leading end of the second tape; first and second tape indexing devices (50, 51) for conveying the first and second tapes (T1, T2) respectively along first and second conveyance paths (60a, 60b) and positioning the cutting points (Q1, Q2) of the first and second tapes (T1, T2) in order at the number and second cutting positions (Lc1, Lc2) and the splicing position; first and second detection devices (52, 53) for detecting respectively the first and second cavities (Ct1, Ct2) of the first and second tapes (T1, T2) conveyed along the first and second conveyance paths (60a, 60b), and the first and second components (e1, e2) stored in the first and second cavities (Ct1, Ct2), at first and second detection positions (Ld1, Ld2) provided respectively in the first and second conveyance paths (60a, 60b); a control device for controlling each operation of the first and second tape indexing devices (50, 51), the first and second cutting devices (54, 55) and a joining device; characterized in that the control device has: a pitch calculating means for calculating the predetermined pitch between the first and second cavities (Ct1, Ct2) based on at least one of the first and second cavities (Ct1, Ct2) detected at at least one of the first and second detection devices (52, 53); a first and second cutting point calculating device for calculating respectively the first and second cutting points (Q1, Q2) of the first and second tapes (T1, T2) from first distance between the first detection position and the first cutting position, and second distance between the second detection position and the second cutting position, and the predetermined pitch (Pc) calculated by the pitch calculating means, based on a first and second component presence signal output after the first and second detections devices (52, 53) detect a switch from first and second cavities (Ct1, Ct2) without the first and second components (e1, e2) to first and second cavities (Ct1, Ct2) with the first and second components (e1, e2); and a first and second cutting position deciding means which control the first and second tape indexing devices (50, 51) and move the first and second tapes (T1, T2) first and second distances (D1, D2) after the first and second component presence signal is output to respectively decides the conveyance positions of the first and second cutting points (Q1, Q2) at the first and second cutting positions (Lc1, Lc2). first and second cutting devices (54, 55) for respectively cutting at first and second cutting positions (Lc1, Lc2) the respective unnecessary sections at the tail end of the first tape and the leading end of the second tape; first and second tape indexing devices (50, 51) for conveying the first and second tapes (T1, T2) respectively along first and second conveyance paths (60a, 60b) and positioning the cutting points (Q1, Q2) of the first and second tapes (T1, T2) in order at the number and second cutting positions (Lc1, Lc2) and the splicing position; first and second detection devices (52, 53) for detecting respectively the first and second cavities (Ct1, Ct2) of the first and second tapes (T1, T2) conveyed along the first and second conveyance paths (60a, 60b), and the first and second components (e1, e2) stored in the first and second cavities (Ct1, Ct2), at first and second detection positions (Ld1, Ld2) provided respectively in the first and second conveyance paths (60a, 60b); a control device for controlling each operation of the first and second tape indexing devices (50, 51), the first and second cutting devices (54, 55) and a joining device; a pitch calculating means for calculating the predetermined pitch between the first and second cavities (Ct1, Ct2) based on at least one of the first and second cavities (Ct1, Ct2) detected at at least one of the first and second detection devices (52, 53); a first and second cutting point calculating device for calculating respectively the first and second cutting points (Q1, Q2) of the first and second tapes (T1, T2) from first distance between the first detection position and the first cutting position, and second distance between the second detection position and the second cutting position, and the predetermined pitch (Pc) calculated by the pitch calculating means, based on a first and second component presence signal output after the first and second detections devices (52, 53) detect a switch from first and second cavities (Ct1, Ct2) without the first and second components (e1, e2) to first and second cavities (Ct1, Ct2) with the first and second components (e1, e2); and a first and second cutting position deciding means which control the first and second tape indexing devices (50, 51) and move the first and second tapes (T1, T2) first and second distances (D1, D2) after the first and second component presence signal is output to respectively decides the conveyance positions of the first and second cutting points (Q1, Q2) at the first and second cutting positions (Lc1, Lc2).