This study was conducted to examine activity of medaka (Oryzias latipes) â-actin promoter (mBP) in common carp(Cyprinus carpio) as the first step towards development of common carp transgenic in country. Gene constructpmBP-hrGFP that consists of mBA promoter and humanized Renilla reniformis green fluorescent protein gene(hrGFP) was injected into cytoplasm of one cell stage of common carp by using microinjector. PmBP-hrGFPconcentration used for microinjection was 50 μg/mL aquabides. Parameters observed were survival rate of embryo(SRe), hatching rate (HR) and expression of hrGFP gene. SRe was calculated before eggs hacthed, while hatchingrate (HR) was after all of eggs hatched. The activity of mBA promoter was analyzed by observation of hrGFP genetransient expression using a fluorescence microscope. The results of experiment showed that SRe (87,5%) andHR (79.2%) of control was respectevily higher than that of injected treatment (75.0% & 61.7%). Expression of hrGFPwas observed firstly at blastula (12 hours after fertilization) to 1-day-old larval stages (24 hours after hatching)with higher gene expression at blastula to late gastrula stages. Percentage of micronjected larvae expressinghrGFP at 6 hours after hatching reached 71.6 ± 6.7%. Conclusion was that mBA promoter could drove hrGFPexpression in common carp, hence it can be used to produce common carp transgenic by changing hrGFP withgenes correlated with important traits in aquaculture.