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