To provide an inside-tank fuel pump which is reduced in number of items and assembling is easy, while decreasing negligence to perform assembling and reducing exchanging cost of a filter element.

A housing member 2 of a fuel pump 1 has a flange member 10, a case member 20 and a support member 30. The flange member 10 is detachable connected to the case member 20, while the case member 20 is detachably connected to the support member 30. The case member 20 has a filter case 22, a pump case 24, a level gauge attachment part 25 and a cap 29, all of which are integrated with each other. Since the case member 20 housing a filter element 23 and a pump main body 26 is unitedly formed and detachably connected to the flange member 10 and the support member 30, assembling portions and steps are reduced among the members. In order to replace the filter element 23, only the case member 20 and the filter element 23 need to be exchanged. Exchanging cost of the filter element 23 is thus reduced.