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Massive stars having a CO core of $\sim$40-60 M$_\odot$ experiencepulsational pair-instability (PPI) after carbon-burning. This instabilityinduces strong pulsations of the whole star and a part of outer envelope isejected. We investigate the evolution and mass ejection of metal-poor verymassive stars which experience PPI. We use stellar models with initial massesof 140, 200, and 250 M$_\odot$ and the metallicity Z=0.004. Their massesdecrease to 54.09, 58.65, and 61.03 M$_\odot$ before the neon-burning owing tomass-loss and He mass fraction at the surface becomes about 20%. During the PPIperiod 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 thelarger amount of mass. Since almost all surface He has been lost by thepulsations, these stars become Type Ic supernovae if they explode. Light curvesduring the PPI stage and supernovae are investigated and are implicated inluminous supernovae. The luminosity created by the interaction of different PPIejecta becomes $M_{\rm bol} \sim -16$ to $-20$. The interaction between thecircumstellar shell ejected by PPI and the supernova ejecta can be moreluminous. These luminous transients could be an origin of Type I superluminoussupernovae and supernovae with precursor.

Mass ejection by pulsational pair instability in very massive stars and implications for luminous supernovae