Example embodiments relate to an internal power supply voltage generating device. The internal power supply voltage generating device may include a start-up voltage generating part, a reference voltage generating part, and/or an internal power supply voltage generating part. The start-up voltage generating part may be configured to generate a start-up voltage using an external power supply voltage. The reference voltage generating part may be configured to generate a reference voltage using the start-up voltage. The internal power supply voltage generating part may be configured to generate an internal power supply voltage using the reference voltage and the external power supply voltage. The start-up voltage generating part may be turned off by the reference voltage generated by the reference voltage generating part. Example embodiments also relate to a method of generating an internal power supply voltage.