Levels of 14 trace elements (Al, Ti, V, Cr, Mn, Co, Ni, Zn, As, Se, Cd, Sn, Hg, and Pb) and 5 arsenic species (arsenite/As(III), arsenate/As(V), monomethylarsonic acid/MA, dimethylarsinic acid/DMA, and arsenobetaine/AsB) were assessed in the gonads of sea urchin samples (Paracentrotus lividus) from North-West Mediterranean Sea (French coast). The samples were collected from 13 sites characterized by different types and levels of chemical contamination. Trace elements levels were measured by inductively coupled plasma-mass spectrometry (ICP-MS) following microwave (acid) digestion in a closed system, whereas As speciation analysis was carried out by ion-exchange liquid chromatography coupled with ICP-MS after microwave-assisted extraction. High levels of trace elements were found in sea urchins sampled from Corsica whereas the samples from Théoule were found to be the least contaminated. From all the analyzed urchin samples, none showed Cd, Hg, or Pb concentrations above the regulatory levels set by the European Community (EC) No. 1881/2006 for seafood or bivalve mollusks. Regarding arsenic speciation, AsB was confirmed to be the predominant species. Inorganic As (As(III) + As(V)) was mainly constituted by As(III), which was quantified in all samples. Methylated As forms (MA and DMA) represent 9 to 23% of the total As.