An embodiment of the present invention discloses a highchair with adjustable seat, including a frame and support device, which are connected to the frame and which form a bearing plane for supporting the frame on a floor. The frame includes at least two substantially parallel uprights which in a position of use of the chair protrude at least partly obliquely above the bearing plane. Further, the highchair includes a part adjustable along the uprights, which is provided with an engaging device for engaging the two uprights, wherein the engaging device includes at least one receiving chamber for engaging part of the way round the upright.