To provide catalyst of high activity as one for a solid polymer fuel cell, and its manufacturing method and a membrane electrode assembly using it.

The catalyst for a fuel cell has metal oxide fine particles and platinum system metal catalyst fine particles carried by a carbon carrier, with a mean particle diameter of the metal oxide fine particles measured by an X-ray diffraction method of 20 nm or less. The manufacturing method of the catalyst for a fuel cell having the carbon carrier carry metal oxide and platinum system metal catalyst fine particles comprises a process 1 of having the carbon carrier carry a metal compound to be metal oxide by calcining and calcine it at 300C or less and at a temperature at which the metal compound turns to be metal oxide, and a process 2 of having the carrier thus obtained in the process 1 carry platinum system catalyst fine particles. The membrane electrode assembly has the above catalyst contained at least in either of the electrode catalyst layers.