Vacuum ultraviolet (VUV) and visible spectra have been measured using a 3m normal incidence and a 50cm Czerny-Turner type spectrometers with CCD detectors, respectively, in order to observe magnetic dipole (M1) forbidden transitions in 2s²2p^x(x=1 to 5) ground and 2s2p excited configurations of highly charged argon emitted from argon discharges of Large Helical Device (LHD). One of observed VUV lines was identified as an M1 transition of ArXII 2s²2p^{3 4}S_3/2-²P_3/2 (648.93Å) by analyzing the spectral broadening, which indicated a relatively high Doppler temperature, and by simulating the time behavior using impurity transport code. Measured temporal behavior of the ArXII line was clearly different from that of low-ionized argon ion stages. Four M1 transitions of ArX, ArXI, ArXIV and ArXV have been also observed in the visible region. Wavelengths of the M1 transitions obtained from the present data are compared with calculated values. In the conference, the first observation of the M1 transition in LHD is introduced and results of the analysis are discussed.