Massive stars having a CO core of \sim 40–60 M _ { \odot } experience pulsational pair-instability ( PPI ) after carbon-burning .
This instability induces strong pulsations of the whole star and a part of outer envelope is ejected .
We investigate the evolution and mass ejection of metal-poor very massive stars which experience PPI .
We use stellar models with initial masses of 140 , 200 , and 250 M _ { \odot } and the metallicity Z = 0.004 .
Their masses decrease to 54.09 , 58.65 , and 61.03 M _ { \odot } before the neon-burning owing to mass-loss and He mass fraction at the surface becomes about 20 per cent .
During the PPI period of \sim 1–2000 yr , they experience six , four , and three pulsations , respectively .
The larger CO-core model has the longer PPI period and ejects the larger amount of mass .
Since almost all surface He has been lost by the pulsations , these stars become Type Ic supernovae if they explode .
Light curves during the PPI stage and supernovae are investigated and are implicated in luminous supernovae .
The luminosity created by the interaction of different PPI ejecta becomes M _ { { bol } } \sim - 16 to -20 .
The interaction between the circumstellar shell ejected by PPI and the supernova ejecta can be more luminous .
These luminous transients could be an origin of Type I superluminous supernovae and supernovae with precursor .