The toy piano is a musical instrument, made as a child's toy, but which has also been used in more serious musical contexts. The instrument was invented in Philadelphia in 1872 by a German immigrant named Albert Schoenhut.

It is often in the form of a scaled down model of a piano, usually no more than 50 cm in width, and made out of wood or plastic. The first toy pianos were made in the mid-19th century and were typically uprights, although many toy pianos made today are models of grands. Prices range from a few dollars to a few hundred dollars.

Rather than hammers hitting strings as on a standard piano, the toy piano sounds by way of hammers hitting metal bars or rods which are fixed at one end. The hammers are connected to the keys by a mechanism similar to that which drives keyboard glockenspiels. This makes it sound more 'tinkly.' Some new toy pianos are electronic.

Toy pianos ostensibly use the same musical scale as full size pianos, although their tuning in all but the most expensive models is usually very approximate. Similarly, the pitch to which they are tuned is rarely close to the standard of 440 Hz for the A above middle C.

A typical toy piano will have a range of one to three octaves. The cheapest models may not have black keys, or the black keys may be painted on. This means they can play the diatonic scale (or an approximately tuned version of it), but not the chromatic scale. Typically, diatonic toy pianos have only eight keys. They can play one octave.

Although primarily thought of as a toy, the toy piano has been used in serious musical endevours. The most famous example is the Suite for Toy Piano by John Cage. Other works in classical music for the instrument include Ancient Voices of Children by George Crumb and a number of pieces by Mauricio Kagel. In improvised music, Steve Beresford has used toy pianos (along with many other toy instruments).

A pioneer of the toy piano is the german composer and pianist Bernd Wiesemann (*1938). He played many concerts with the toy piano in Germany in the 1970s and 80s. In 1993 he released the CD Neue Musik für Kinderklavier (new music for Toy piano), containing compositions by John Cage, Karlheinz Stockhausen, Ratko Delorko, Andreas Kunstein, Frank Scholzen, Joachim Herbold, Carlos Cruz de Castro, Francisco Estevez and Bernd Wiesemann. In 2004 he released the SACD das untemperierte klavier (the not-so-well-tempered clavier), containing new contemporary works.

In 1997 the pianist Margaret Leng Tan released the record The Art of the Toy Piano. On it, she plays a number of pieces written specially for the toy piano as well as arrangements of other pieces, including Ludwig van Beethoven's Moonlight Sonata and The Beatles' "Eleanor Rigby".