We present an experimental demonstration of three-dimensional terahertz radar based on multi-directional leaky-wave scanning. The radar consists of a leaky-wave antenna that allows for one-dimensional beam steering by sweeping frequency around 300 GHz. The 3D positions of objects placed in front of the antenna can be reconstructed by synthesizing radar signals acquired at various azimuthal angles against the objects through a sparse signal reconstruction algorithm. As a proof of concept, we present a result of 3D position detection of metal rods.