A base station apparatus for transmitting a reference signal in a wireless communication system is provided in which a processor generates the same sequence for resource elements (REs) allocated to each layer for reference signal transmission and spreads or covers Walsh codes for a user equipment-specific reference signal sequence such that sequences generated for the REs can be orthogonal to each other on a time axis. The Walsh code spreading or covering by the processor is applied on a frequency axis based on a plurality of resource blocks (RBs) or based on a pair of RBs such that mutually different sequences having mutually different sequence values can be mapped between RBs or between pairs of RBs. A transmission module transmits the reference signal, to which the generated reference signal sequence is applied to user equipment via each layer.