The present invention provides sustained-release oral administration preparations containing the phenylalanine compound of the formula (1) wherein A represent the formula (2) and the like； B represents an alkoxy group and the like； E represents a hydrogen atom and the like； D represents a substituted phenyl group and the like； T, U, and V represent a carbonyl group and the like； Arm represents a benzene ring and the like； R1 represents an alkyl group and the like； R2, R3, and R4 may be the same or different from each other and represent a hydrogen atom, substituted amino group and the like； and J and J' represent a hydrogen atom and the like, or pharmaceutically acceptable salts thereof as an active ingredient in either form of a coating preparation or a matrix preparation. This active ingredient has a relatively shorter half-life in blood plasma, and the preparations having continuance of the effects are provided by the present invention.
