For providing a design apparatus for designing a small diode connector durable for overcurrent flow easily in low cost, and a design method for designing the diode connector, and a diode connector durable for overcurrent flow to be small in low cost, the design apparatus 1 having a plurality of lead frames, a diode chip and a bridge and solder brazing these components includes a determining unit determining one of the name of the brazing alloy to be used as a solder and a total volume of the lead frames and the bridge when the other of the name of the brazing alloy and the total volume of the lead frames and the bridge is inputted, based on the inputted other and a correlation data of the total volume and a heat temperature of the diode chip.