To provide a built up post for an alter service which is capable of securing a definite connected state with a simple assembly and shortening the built up post by disassembling.

A first wooden-made post member 13 and a second wooden-made post member 15 are provided with a first projecting post piece 21 and a second projecting post piece 23 so as to extend their one side surfaces. Second tapered tops 25 and 27 are provided at the tips of the second projecting post pieces 21 and 23 where first and second fit-in grooves are formed herein. First and second tapered receiving grooves 41 and 43 are formed on the base part of the first and second projecting pieces 21 and 23. Wooden-made first and second small pieces 37 and 39 are inserted into the first and second post members 13 and 15 so as to project into the first and second receiving grooves 41 and 43 from the side surface side. The first and second tops 25 and 27 of the first and second projecting post pieces 21 and 23 are fitted in the second and first receiving grooves 53 and 51, thereby connecting each other.