Abstract: The present invention relates to a straightly assembled block comprising engaging assembly means configured in male and female types, first ends of which can be coupled to each other, such that male and female piece blocks can be assembled by connecting the same to each other straightly, and the engaging assembly means are improved such that wear is prevented in spite of repeated separation/coupling, thereby maintaining continuous assembly power. To this end, the male and female piece blocks have engaging assembly means, first ends of which protrude in arc shapes, and the second ends of which are coupled to each other. Alternatively, connecting blocks have engaging assembly means formed on both ends thereof in different types. The engaging assembly means formed on the piece blocks or on the connecting blocks comprise a recessed portion and a protruding portion.