We observed the bound-state beta decay of fully ionized ²⁰⁷Tl nuclei circulating in a storage ring. It is the first direct measurement of bound-state beta decay. ²⁰⁷Tl nuclei were produced by the projectile fragmentation, separated by fragment separator and injected in the storage ring. Using the Schottky diagnostics the decay time spectrum of bare ²⁰⁷Tl and hydrogen like ²⁰⁷Pb ions which are the daughter nuclei of bound-state beta decay were measured. Observed decay-rate ratio between bound-state and continuous-state beta decay was 0.18(2). This value is consistent with the theoretical calculation.