A direction indication lamp control device includes: a pulse signal generation unit that generates a pulse signal; a current control element having one end to which power supply voltage is supplied, a control terminal to which the pulse signal is supplied, and the other end which outputs a drive current, the other end of the current control element being connected to one end of an external direction indication switch, and the other end of the direction indication switch being connected to a direction indication lamp; and a leak detection unit that causes the pulse signal generation unit to decrease the amplitude of the pulse signal in a case where the drive current corresponding to a pulse wave of the pulse signal is equal to or less than a leak detection current value during a leak detection period.