A memory module includes a plurality of memory units and an assembling holder. Each of the memory units includes a memory substrate, at least a memory chipset having a predetermined memory capacity mounted on the memory substrate, and an electric terminal provided at a lower edge portion of the memory substrate. The assembling holder includes an elongated unit housing having an elongated receiving slot extended therealong and a signal terminal provided along the unit housing, wherein the electric terminals of the memory substrates are detachably inserted into the receiving slot of the unit housing to electrically connect the electric terminals with the signal terminal, such that the memory units are alignedly and detachably mounted along the receiving slot in an edge to edge manner.