An information record medium (1: DVD) has a record track recorded with record information to be reproduced by an information reproducing apparatus (S2). The information reproducing apparatus is provided with a read device (80), and performs a reproduction while moving the read device along the record track at a predetermined reading linear velocity, the record information is divided into a plurality of first data groups (30: VOBU), each of which is a unit able to be accessed by the information reproducing apparatus, recorded on the record track. Lowest reading rate information (212) indicates a minimum requirement of a reading rate for the information reproducing apparatus to reproduce a reproduction unit, which comprises at least one of the first data groups and which is to be reproduced by the information reproducing apparatus such that a sequential logical meaning of the reproduction unit is continuous. The lowest reading rate information is recorded on the record track at one portion (LI, 11, 41) different from another portion where the record information is recorded.