The present invention relates to a method and apparatus for measuring a signal. According to one embodiment of the present invention, a signal measuring method may comprise the steps of: determining whether or not a current subframe corresponds to a measurement period; measuring a serving cell signal when the current subframe corresponds to the measurement period; determining whether a current measurement mode is a normal scan mode or a short scan mode in which a serving cell signal is more frequently measured than in the normal scan mode; determining whether or not the measured serving cell signal is less than a preset low signal threshold value when the current measurement mode is the normal scan mode; and changing the current measurement mode to the short scan mode when the measured serving cell signal is less than the low signal threshold value. According to one embodiment of the present invention, a system signal measuring method and apparatus which can quickly reflect the surrounding environment while efficiently using power is provided.