A double ballistic point contact (D-BPC) structure, where two point contacts are placed in series with a separation of ${L}_{\mathrm{sp}}$, is fabricated by focused Ga-ion beam scanning. Conductance characteristics for an ${L}_{\mathrm{sp}=200}$ nm sample show multiple peaks in their gate-bias dependences. These peaks probably originate from ballistic transport through zero-dimensional levels. The ${L}_{\mathrm{sp}=400}$ and 800 nm samples show step structures similar to those of a single point contact. Although plateau resistance values differ from the quantized values (${R}_{n}$) with a zero magnetic field, it is found that they approach ${R}_{n}$ as the magnetic field increases.