The present invention relates to a contrast agent containing a semi-fluorinated carbon compound. The present invention provides a) a semi-fluorinated compound represented by formula I: CF3- (CF2) x- (CH2) y-CH3 (I) Represents an integer from 1 to 8 and y represents an integer from 2 to 10. b) An aqueous emulsion comprising a triglyceride miscible with the semi-fluorinated compound at 20 ° C .; and c) an emulsifier. [Selection figure] None【課題】セミフッ化炭素化合物含有造影剤【解決手段】本発明はa)式Iで表されるセミフッ化化合物: CF3-(CF2)x-(CH2)y-CH3 (I) (式中、xは1乃至8の整数を表し、及びyは2乃至10の整数を表す。)b)20℃にて前記セミフッ化化合物と混和可能である、トリグリセリド;及びc)乳化剤、を含む水性エマルションに関する。【選択図】なし