Energy-dispersive x-ray diffraction experiments were carried out to investigate the structure of phase transitions under high pressure. It was found that the zinc blende (B3) to rock salt (B1) phase transition pressures of Zn0.93Mn0.07Se and Zn0.76Mn0.24Se bulk crystals are found 11.8 ± 1.5 and 9.9 ± 0.5 GPa, respectively. The respective bulk moduli are 61.8 ± 0.8 and 60.5 ± 0.8 GPa. The pressure-induced zinc blende (ZB) to rock salt (RS) structure phase transition is interpreted as a signature of the semiconductor to metal transition for Zn1-xMnxSe. The above interpretation is further corroborated by the observation of the disappearance of the longitudinal optical phonon at the pressure where the ZB to RS structure transition occurs.