In order to meet the demand of a research platform for intelligent robotics, a humanoid robot named Saika-4 is developed. The Saika-4 is a self-sustained biped robot equipped with two arms and a robotics head. The Saika-4 is designed so as to be light weight, low cost and human size. The weight will be about 47 [kg], and the height is about 1300 [mm]. The Saika-4 will have 30 DOF in total, that is 6 DOF for each leg, 7 DOF for each arm, 1 DOF for each hand and 2 DOF for robotics head. The Saika-4 is equipped with a PC, batteries, a wireless ethernet modem, a gyroscope, and motor drivers in the body. Furthermore, the Saika-4 is equipped with a gravity compensation mechanism using springs in the legs. This paper presents the design of a humanoid robot Saika-4 and the progress of the project. The details of the gravity compensation mechanism is also presented.