This paper is a report of occupational categories in professional career of British architects. I sampled 539 architects who were chosen from Howard Colvin's "Biographical Dictionary of British Architect". I found the rates of each categories in specially fixed terms, and illustrated them by a diagram. I classified the architects into four descriptions, according to occupational categories ; (1) Category I : Architectural trades. (2) Category II : Owners and specialists of several fields. (3) Category III : Engineers. (4) Category IV : Generalists of architectural works, mainly professional architects, builders and surveyors. The diagram shows following items below ; 1) Architects having been Category II, were in the heyday of their rate in the decade of 1650 s. 2) Architects having been Category I, were in the heyday of their rate in the decade of 1720 s. 3) Architects having been Category IV, show a step-up in the rate after 1770 s. 4) Architects having been Category III, were a few.