In this paper we present RUBIQ, a polymorphic ubiquitous network testbed. RUBIQ works on StarBED, which is a network testbed consisting of hundreds of PCs connected to each other. RUBIQ consists of a set of subcomponents such as RUNE and QOMET that make it possible to simulate ubiquitous network systems in huge scale that can hardly ever be experimented in the real world. We illustrate the structure of the testbed, how it functions, and the results of some of ubiquitous network system simulations. We show some results demonstrating that the testbed achieved an accurate simulation of a pedestrian tracking system by using appropriate modules, such as a wireless communication emulator and processor emulator. Key words: ubiquitous networks; wireless network; distributed testbed; supporting software; simulation; emulation 1 RUBIQ In this paper we present RUBIQ, a polymorphic ubiquitous network testbed implemented on StarBED, and a couple of its subcomponents such as RUNE and QOMET. RUBIQ en...