NTSC-J or "System J" is the informal designation for the analogue television standard used in Japan. The system is based on the US NTSC (NTSC-M) standard with minor differences. While NTSC-M is an official CCIR and FCC standard, NTSC-J or "System J" are a colloquial indicators.

The system was introduced by NHK and NTV, with regular color broadcasts starting on 10 September 1960.

NTSC-J was replaced by digital broadcasts in 44 of the country's 47 prefectures on 24 July 2011. Analogue broadcasting ended on 31 March 2012 in the three prefectures devastated by the 2011 Tōhoku earthquake and tsunami (Iwate, Miyagi, Fukushima) and the subsequent Fukushima Daiichi nuclear disaster.

The term NTSC-J is also incorrectly and informally used to distinguish regions in console video games, which use televisions (see Marketing definition below).

Japan implemented the NTSC standard with slight differences. The black and blanking levels of the NTSC-J signal are identical to each other (both at 0 IRE, similar to the PAL video standard), while in American NTSC the black level is slightly higher (7.5 IRE) than blanking level - because of the way this appears in the waveform, the higher black level is also called pedestal. This small difference doesn't cause any incompatibility problems, but needs to be compensated by a slight change of the TV brightness setting in order to achieve proper images.

YIQ color encoding in NTSC-J uses slightly different equations and ranges from regular NTSC. ${\displaystyle I}$ has a range of 0 to +-334 (+-309 on NTSC-M), and ${\displaystyle Q}$ has a range of 0 to +-293 (+-271 on NTSC-M).

YCbCr equations for NTSC-J are ${\displaystyle C=(Cb-512)*(0.545)*(\sin \omega t)+(Cr-512)*(0.769)*(\cos \omega t)}$, while on NTSC-M we have ${\displaystyle C=(Cb-512)*(0.504)*(\sin \omega t)+(Cr-512)*(0.711)*(\cos \omega t)}$.

NTSC-J also uses a white reference (color temperature) of 9300K instead of the usual NTSC-U standard of 6500K.