We present results from Chandra observations of SDSS J1004+4112, astrongly lensed quasar system with a maximum image separation of 15".All four bright images of the quasar, as well as resolved X-ray emissionoriginating from the lensing cluster, are clearly detected. The emissionfrom the lensing cluster extends out to approximately 1.5 arcmin. Wemeasure the bolometric X-ray luminosity and temperature of the lensingcluster to be 4.7×1044 ergs s-1 and 6.4 keV,consistent with the luminosity-temperature relation for distantclusters. The mass estimated from the X-ray observation shows excellentagreement with the mass derived from gravitational lensing. The X-rayflux ratios of the quasar images differ markedly from the optical fluxratios, and the combined X-ray spectrum of the images possesses anunusually strong Fe Kα emission line, both of which are indicativeof microlensing.