Applying downsized semiconductor detectors to PET cameras makes it possible to achieve high spatial resolutions. On the other hand, a difficulty in obtaining a high packing ratio of detectors arises from this downsizing. When detectors which construct a gantry are increased significantly according to downsizing, the volume of electronics becomes large and limits packing. Therefore, increase of detectors results in low packing ratio of detectors. As a solution of the packing problem, we propose using position sensitive type semiconductor detectors whose one of electrodes is a resistive plane. In such detectors, several charge collection electrodes are made on the resistive electrode and detection positions are identified by difference of collected charges among electrodes. Using such detectors contributes to decreasing electronics to be needed, and therefore an achievement of high packing can be expected. We report on attempts of two dimensional position sensitive CdTe detectors for a development of a PET camera using them. In our development, it is supposed that detector units of the camera are constructed by stacking two dimensional position sensitive semiconductor detectors whose thickness is small. Detection positions in the detector unit can be determined three-dimensionally by structure of the unit. A high spatial resolution in transaxial plane is guaranteed by thinness of the detectors. An axial detection position and a depth of interaction are specified by position sensitivity of the detector. Position resolution of the detector varies according to layout of charge collection electrodes. In this paper, some electrode layouts were attempted and evaluated with CdTe detectors (detector size: 20mm x20mm xl.Omm thickness).It was confirmed that a relation between actual detection position and calculated position was not linear. As an attempt to improve the un-linearity, we tried to connect external resistances among collection electrodes.